Can dieseling damage the barrel of an air rifle? I can't help it but the concept of dieseling gives me an idea, that I probably shouldn't go through with.
no but it could break the spring and don't even think about doing it, you won't like the outcome
@marflow. Marflow, that makes me twice as curious! What actually is the outcome that I'll so greatly dislike?
It can blow out piston seals, break springs, and in severe cases, I've heard of it actually blowing the end plug out of the compression tube. Don't do it!
Ruin't a seal with the quickness.
Based on the necropsy, I'm not sure there is any acceptable level of dieseling with polymer seals.
Why I didn't think to sacrifice this seal at the altar of the chronograph? No idea.
Hmm... now I'm thinking... which fuel is hottest? Which gun is easiest to change seals?
We're gonna need a volunteer from the audience...
My dreams of taking a cape buffalo with my springer are dashed lol.
Every, repeat, every springer needs a little dieseling.
What you do not want is combustion.
There are stories (you don’t want to know) about young boys pouring a can of three-in-one oil into the barrel of the Daisy rifles.
For about 4-5 shots the outcome achieved the intended purpose:
More noise and some speed.
But, those pressed metal and plastic rifles could only take so much.
The last time....BOOM!
Pieces everywhere, including some stuck in the arms of the shooter.
Modern springers require very little oil in the combustion chamber and my rifles received 1-2 drops every 500 shots. Period.
Yes the first shot might be a little smokey and a might louder than normal. After that shot the noise will go away and the smoke will lessen.
The smoke from the dieseling is very apparent when shooting indoors.
Remember 1-2 drops in the chamber after 500 shots..
And spread it around by cocking and un-cocking the arm withe the rifle held in various positions..
Stay safe
Diesel (Noun)
A type of internal-combustion engine that burns fuel oil: the ignition is brought about by heat resulting from air compression, instead of by an electric spark as in a gasoline engine.
Diesel (Verb)
To ignite a substance by using the heat generated by compression
Every, repeat, every springer needs a little dieseling.
What you do not want is combustion.
There are stories (you don’t want to know) about young boys pouring a can of three-in-one oil into the barrel of the Daisy rifles.
For about 4-5 shots the outcome achieved the intended purpose:
More noise and some speed.
But, those pressed metal and plastic rifles could only take so much.
The last time....BOOM!
Pieces everywhere, including some stuck in the arms of the shooter.
Modern springers require very little oil in the combustion chamber and my rifles received 1-2 drops every 500 shots. Period.
Yes the first shot might be a little smokey and a might louder than normal. After that shot the noise will go away and the smoke will lessen.
The smoke from the dieseling is very apparent when shooting indoors.
Remember 1-2 drops in the chamber after 500 shots..
And spread it around by cocking and un-cocking the arm withe the rifle held in various positions..
Stay safe
Frank,
You've got it backwards. Combustion is the quiet consumption of lubricant. Dieseling is the detonation part of it. Diesel engines don't do what they do quietly! As far as putting oil in the COMPRESSION (not combustion) cylinder goes, I haven't put any in since I converted my last leather sealed gun to a synthetic seal, about 25 years ago. Properly lubricated modern guns don't need any oil in the cylinder!
Cunningham's Law has entered the chat...
So “Properly Lubricated” does not mean oil?
Oh, yeah you are right.
Use Vaseline or KY3!
2 cycle would be the best of both worlds....
So “Properly Lubricated” does not mean oil?
Oh, yeah you are right.
Use Vaseline or KY3!
That would depend on where you are planning on putting your guns.
In the springer world, properly lubricated means a thin film of a moly grease, or Krytox around the sides of the piston seal. It lasts for thousands of shots, with no dieseling, or any need for any oil in the compression tube.
I once put KY in a suppressor.
It worked well enough, wetness wise, but caused some rust on the gun.
MANY years ago, with the help of a great chemist, and an excellent airgunner, we conducted some controlled tests to see if the shortcomings of the Barakuda design could be overcome.
So, we took a very robust Mendoza 800 action, created a bronze faced piston, and loaded the pellet skirts with "soaps"
For those that are not familiar with how soap is made, it is basically a grease/fat that has been made to react with a strong alkali.
In the same way you can make soaps out of olive oil, or almond oil, or jojoba oil, for "beauty" purposes, you can make soaps out of any hydrocarbon.
The very common in the old days "lithium grease" was, in reality, a soap.
So, we conducted controlled tests with different bases and different "oxigenants".
We got VERY mixed results, from the exteremely violent piston bounce that even re-cocked the action, to the more subtle "addition of energy" to an already powerful airgun.
We DID NOT achieve anything that had not been achieved before in the Daisy V/L system and we concluded that the small gain achieved in the region where the controllability and accuracy were still usable, meritted the action, cost, reduced life of components, and effort.
From those same experiments, we concluded what was the RANGE of pressures and temperatures that existed at the moment of ignition in the compression chamber, numbers that have been validated recently by calculation from the energy balance side, as well as from chemical kinetics.
BEYOND the experimental phases, the truth is that there was a strong reason for the V/L system to die.
PERHAPS now a days, with better materials, tolerances, and technologies it could be better implemented, but with the current prices of stuff, I would not see the advantage.
We now have the knowledge to make AIR guns yield 23-24 ft-lbs without any "dieseling", simply by using basic physics.
So,IMHO, there is no NEED for it.
You can use it, at the expense of reduced life in the spring and seals.
As usual, it's up to each one to decide what they want to do with THEIR stuff.
HTH, keep well and shoot straight!
HM
Best soap I ever made was bacon/ham grease with pumice. Omit pumice for use on hair 😉
Don't put the pernil fat, that goes mineral spirits, for the lathe.
I don't understand the current obsession with superfatted (greasy) soaps. You're not clean, tub/shower is a mess, bad for the septic.
Gimme a bar of Zote.
Use of lithium in batteries has raised the price, as a result, lithium in grease has largely been replaced by calcium sulfonate.
This is an old thread which caught my attention. I have never seen a rigorous review explaining how to safely control the intentional dieseling of air gun pellets. People just seem to add varying amounts of whatever oil or grease they have laying around. That certainly increases the power of a shot due to the additional pressure and heat of the combustion. I'm gathering info now with my .22 Gamo Maxxim and .30 Hatsan 130, using a $10 DIY device to precisely dispense a suitable fuel (Crisco, not petroleum) into the pellet.
As a rule of thumb I've found that adding about 1% of the weight of an 18gn .22 pellet in Crisco, or about 1/4 of the amount which fills a pellet skirt, is a safe level at which to begin power testing a gas piston break barrel. It is impossible to get consistent accuracy and to limit the amount of fuel to a safe amount unless you are able to precisely and repeatedly control the amount of fuel added down to about 0.2 grains per pellet. The key is to make a small device which uses a regular bolt to slowly depress the plunger on a 1ml lubrication syringe as the bolt is turned. That way you can cleanly and precisely apply the fuel directly to the pellet skirt and not accidentally add so much that it immediately damages the rifle. A person also needs a chronograph to measure the results, and a digital grain scale to weigh things.
I occasionally jump around to different airgun forums checking the classifieds, and lately I've been searching different forums and YouTube for info about intentional dieseling for power gain. None of the experiments and results I've seen were even up to the level of an intro engineering class. People keep burning piston seals and breaking mainsprings simply because no one has ever bothered to do a basic engineering review of the process. And that, I believe, is because they didn't focus on the fundamental problem of how they were going to accurately dispense the very small amounts of fuel involved.
I'm in the process of shooting a few hundred dieseled shots through my Maxxim this month, I've already shot a few dozen dieseled pellets through it at about 65% power increase. Now I'm working my way through a couple of hundred more shots at about 50% power increase (16 to ~24fpe on the Maxxim), interspersed with dry pellets to verify that velocities drop back to normal again after a dry shot or two.
I expect the .30 Hatsan 130s to hold up well to a 50% power increase from dieseling as well, getting it up to about ~45fpe from a 30foe baseline. The real key to this is having a way to accurately dispense the fuel in the correct and very tiny amounts (starting at about 1/4 of the capacity of a pellet skirt). Then it's quite easy to test the effects of dieseling in and it significantly reduces the risk of immediately damaging your seals or O-rings.
I'll start a new thread on intentionally induced dieseling with pictures of the DIY control used to exactly measure out and apply the amounts required for safer testing and reproduceable results once I have more comprehensive data. I have much better PCP airguns now but I still have fond memories of my first FWB 127 Magnum springer from the late 1970s. I wish only that I'd understood as much about mechanics and engineering back then as I do now.
JP
None of the experiments and results I've seen were even up to the level of an intro engineering class. People keep burning piston seals and breaking mainsprings simply because no one has ever bothered to do a basic engineering review of the process. And that, I believe, is because they didn't focus on the fundamental problem of how they were going to accurately dispense the very small amounts of fuel involved.
Full disclosure, my engineering level is basic, I JUST discovered the formula for calculating bolt weight based from a target bolt velocity. If it makes me feel any better (it does) at least 3 machinists or engineers (FFL manufacturers) told me flat out that there was no such thing. So that 🤣
My entire ownership of spring piston guns is post 2014, and most are synthetic seals. The leather models are toys, and the idea of trying to squeeze 100fps over the reloading manual's MAX loading... it all feels like a camper-trailer demolition derby. Poof.
There was the thought in my mind of introducing the fuel directly to the chamber or transfer port via a solenoid actuated volumetric metering device, then I moved on to having the piston energy contribute to atomization, such as crank-case pressure is used to pump fuel in 2-smokes.
However, I was LDC deficient. Any dieseling which occurred was deemed far too loud, never another thought was given.
Plus... dieseling bad. M'kay? 🧐
Your idea of precisely metering fuel seems like a step in the right direction. Crisco seems prone to greasy fouling. You getting that?
After reading Hector's comments above, I though of gas operated rifles. You see, Hector got me thinking about converting a gas-op semi auto from DI to (my choice of) piston. His words, paraphrased "Why haven't you converted them all already?" 🤪
Solid motivation Bro. Thanks.
Going back to Hector's comments above, I feel like some of the issues surrounding effective use of dieseling have to do with tuning the reciprocating assembly, gas port diameter, and especially the spring.
What would happen if the piston were much lighter?
How about the spring?
What if, instead of slamming the hydrocarbon fuel, how about we just touch it?
"Those who don't know history are doomed to repeat it"
This didn't work out too well.
https://www.pyramydair.com/blog/2006/05/weihrauch-barakuda-el54-ether-injection-air-rifle/
When I first got into black powder I used Crisco to seal the chambers on a revolver. This was on a hot July afternoon. Needless to say, between the ambient temperature and the gun heating up from discharges, I soon had a rather runny mess on my hands. Crisco may work in lubing pellet bases but I suspect that's under ideal, controlled conditions. Anecdotal evidence from Mendoza owners appears to show that the addition of volatile substances, while certainly boosting fpe, produces substantial variations in fps and, I imagine, less than pleasant shot cycles, neither of which contribute to accuracy. Most accounts I've seen report a return to conventional lubrication.
Crisco melts around 117F and it remains soft enough to be dispensed through a blunt needle from a 1ml syringe when it gets cool. Both Vaseline and lard have lower melting points, Vaseline especially tends to sag out of the pellet as it gets warm. Oil ignites too quickly and sort of toxic, a pure frying fat like Crisco has a high flash point and combusts more slowly with less chance to damage things than oil. A 1ml syringe with micro-control on the plunger can dispense the correct test amount ~0.1 grain of Crisco into a pellet at the time it is being loaded. Not ideal for hot desert work but it's only on the butt of the pellet for a short amount of cock and aim.
What people who don't work with compression may not consider is that merely doubling 2x the power of a pellet shot by adding fuel to the pellet skirt might briefly stress the edges of the piston seal with several times that level of pressure, mixed with a short flash of hot combustion gases.
People get carried away trying to make a 30fpe magnum out of 5fpe BB gun (me at 14). I didn't have any other options back then. Now almost anyone can just order a 30fpe break barrel from 177 to .30 and it shows up in a week. And people usually don't know how to measure out the small amounts needed for safe testing. They can't even get started on a useful analysis without a tool like that, and a chrony and a grain scale. After that it's just a basic recipe, add too much Crisco and you risk ruining the cake.
So this information is really for the folks with a mechanical focus who like working with numbers and who are on close terms with their digital scales and chronographs and work benches.
I mostly want to provide some conservative guidance on how a person can significantly reduce the chances of immediately breaking their break barrel air rifle by intentionally induced dieseling. While at the same realizing modest (25% to 50%) increase in power with consistent velocity between shots.
I'll eventually post a more thorough summary, it won't be complete until I can verify whether a couple hundred dieseled shots +50% power will break my .22 Maxxim or .30 Hatsan 130s. And if I pop a seal trying it's really no big deal. I'll learn a lot more about that airgun by replacing the piston seal that I'd ever learn by just shooting the thing.
I began by filling the skirts of some 18.13gn .22 pellets with each of the 3 fuels. A full skirt of Crisco weighs about 2.2% of the weight of an 18.13gn pellet. All 3 fuels gave power increases in the same x1.67 range, with residual vapor and varying velocities indicating too much fuel for complete combustion. So I am comfortable beginning with about 1/4 of that amount, or about 0.10 grains of Crisco per 18 grain pellet as a reasonable safe amount for initial power testing.
The key to the whole thing is to make an inexpensive, easy to use device which can precisely and consistently measure and then cleanly dispense the fuel into the pellet. Since weight and volume are related, the amount required is converted into ml. If I get ambitious I'll try to post a few pics of one later tonight with a few better number as my final post on this old thread.
I expect to be ready to post a summary of my results on controlled dieseling in my .22 Maxxim in a new discussion thread by the end of the month. It'll probably take an additional month after that to get the numbers for the 130s since it's so hard to cock. Though when testing that one I'll mount a barrel holder (clamp open on one long side) on the wall next to me. Just a couple of pieces of 2x4 about 14 inches long, and secured to the wall about an inch apart. Just enough space to slide the barrel sideways in between the boards to hold it. Then I swing the entire body of the rifle up and over with both arms to let gravity do most of the work of cocking. And while testing I've occasionally used a piece of PCV tube lined with duct tape and mounted on a wall to hold the barrel of my Maxxim while I am cocking it.
Pictures of the DIY micro-ml dispenser will help to explain how to measure and calibrate things. Then a person could accurately measure how much Crisco is being dispensed and limit it to a safer initial amount for testing. If you are the kind of person who will just get mad at yourself if you accidentally ruin a piston seal based on some stranger's internet post, then don't do it, a few extra fpe hardly matter these days. This topic is mostly for people with time and with expendable air rifles to work on for fun, and in the pursuit of scientific knowledge. You can usually spot them because they always wear their safety glasses.
A properly lubed spring gun NEVER needs added oil.
A properly lubed spring gun NEVER needs added oil.
I put ONE DROP in the R9 spring, during a lapse of judgement.
After thousands of shots without any such treatment, I have no idea what compelled me to do this. Derp?
Two drops ran out of the compression tube, then it dieseled randomly for months.
Managed to screw up the only paper shooting I've done in years, the wadcutters past 30 thread.
Know that feeling of "what if" when getting involved with airguns.
In this case, think "we" have already figured out really good/efficient ways of sending lead projectiles down range by burning fuels. Pretty much defines a "firearm" even if your ignition source is compression and the fuel starts out as a liquid. Are basically using a really over complicated ignition system.
There are propane powered nailers and paintball markers.
They aren't firearms if the combustion moves a piston. They are if it moves the projectile.
Sounds like a good way to blow up a gun and maybe yourself though.
That ether injection system got bad reviews and probably was a firearm under US law.
Was not aware that Tippman still made those propane markers....must be a few of them out there still running.
If the HW Barakuda ever got put to the US legal standards, am unaware of the outcome. HAve seen them as collectors rifles and do appreciate the heavier/stronger pellets that they spawned.
Daisy V/L seems a whole lot like adding burning lube to pellets. Did use a little ball in the air tube's port to keep the back pressure out of the compression chamber. You could shoot a pellet, although not really fast.
This will be my last post in this thread ... sighs of relief
Here's an demo example (pictures at bottom) of a simple DIY device which can dispense Crisco fairly accurately in increments of about 0.020ml or ~0.10 grains. A commercial repeating micro-dispenser which does the same thing is called a Repeater Pipette. I've used one in a chem lab, they are very accurate with viscous liquids down to millionths of a milliliter, but they usually cost at least $250.
This DIY version was thrown together in under an hour, I made it open top so you can figure out what's happening just by looking at it. It isn't t as accurate or as easy to use as one of those pricey Repeater Pipettees. But it worked well enough for my initial testing purposes and it only cost me about $15 to make.
I took a 5 inch long piece of 2x2, cut a groove down the center of one long side, just wide and deep enough to hold a 1ml lubrication syringe. Then made a thin cross cut 2 inches from one end for the finger pads on the syringe to slide into. Then glued a nut on the plunger end of the syringe groove and threaded a 20 threads/inch bolt into the nut. When lined up with the syringe plunger, the end of the bolt presses the plunger down and dispenses a very thin noodle of Crisco out of the blunt syringe needle. When the bolt is turned slowly and a couple of seconds allowed for the needle tip to empty before repeating, it actually works surprisingly well.
So yesterday I tested some more 18.13 grain pellets in a Maxxim with the device to see if the Crisco dispenser was accurate enough to produce any useful results. Yes it was, and the results were an unexpected surprise.
Here's how I tested the device:
Round 1: First I shot 8 dry pellets to get a baseline power level (16.3fpe, velocity spread 32f/s),
followed by 8 dieseled pellets loaded using 1/4 turn on the Crisco dispenser bolt, filled the skirt maybe 1/5th of the way full. (27.1fpe, power factor x1.66, velocity spread 34f/s - just 2f/s more than the dry pellets)
Round 2: Shot another 8 dry pellets to check for # of dry shots before power fell back down to around the baseline of ~16.3fpe. It went back down to baseline on the first dry pellet and stayed there. Good data point, indicating that there was enough air in the compression chamber to fully combust the amount of Crisco (1/4 bolt turn) on the previous 8 dieseled shots.
Then 8 more dieseled pellets loaded using 1/2 turn on the Crisco dispenser bolt (27.1fpe, power factor x1.66, velocity spread 34f/s). Identical power increase results as when I only used 1/2 of that amount of Crisco in Round 1.
That's a good data point, indicating that the amount of available air was NOT sufficient to burn any more more Crisco than had been burned in Round 1. So using any more Crisco than the smallest amount used in Round 1 won't actually increase the power. But larger amount will increasingly degrade consistency of shot velocity due to the film of unburned Crisco left in the rifle by the overloaded pellets.
Round 3: Shot another 8 dry pellets. This time it took about 5 shots before before the velocity dropped back down near the baseline power level. Another clear indication of unburned Crisco remaining in the rifle from the previously dieseled pellets.
Then shot 8 more dieseled pellets loaded with 1 full turn on the Crisco dispenser bolt. It appeared visually to fill the skirt about 2/3 of the way, and was 4 times the amount used in Round 1.
Here's that surprise result again and why it's so interesting and important to test these things. The average ~66% power increase was exactly the same for all 3 different amounts of Crisco just tested. And exactly the same as when the same pellets were filled to the top using about 6 times as much Crisco as was used in the Round 1 test.
This tells me a few important things. I've shot about 130 dieseled pellets at over 65% power increase out of my Maxxim so far, plus several hundred dry pellets. Even though that constant increased shock can't be good for the rifle in the long run, it still works fine now at the same performance level as when new.
And only a very small amount of Crisco, less than about 1/5th of a skirt full, will be able to completely combust given the limited amount of available air for each shot in the Maxxim. Using a larger amounts of Crisco, all the way up to a full pellet skirt, will produce almost exactly the same 66% power increase as when only filling the pellet skirt about 1/5th full. Use any more than that and the velocity variation increases due to increasing amounts of residual unburned fuel remaining in the gun after each shot.
It also tells me I would need to either adjust my Crisco dispenser to accurately dispense even smaller amounts if I am going to be able to test the increasingly smaller amounts of Crisco needed. I might just use a bolt with 40 tpi (threads per inch) instead of the 20 tpi bolt in there now to dispense amounts only 1/2 as large as before.
At those very small amounts of a tiny fraction of a ml it's increasingly difficult to be both sufficiently precise to test below the point at which the 65% power level just starts to drop due to having less Crisco available than air to burn it. That's the range I want to continue testing at, with Crisco only filling 1/6th or less of the volume of the pellet skirt. That's a very small amount. So small that you'd hardly even notice it in the back end of a pellet, but it's still about enough to give the same full 65% Crisco power boost of a fully filled pellet.
I'll probably just buy a mechanical Repeater Pipette dispenser calibrated in 100ths of a ml which can accurately handle the tinier amounts needed to consistently get the power factor down from x1.66 to about x1.5 (a 50% increase). That way I can also use it to compare to the results using my DIY Crisco dispensers. I'd like to get down to a ~50% power increase which I think will be a reasonably safe top power limit for Maxxim over the long run.
Note that almost all complaints about dieseling which have mentioned serious problems have been due to over oiling or over lubricating with petroleum products. No big surprise there, oil detonates so hot and fast on compression that it just isn't well suited for safe dieseling purposes. Crisco is a much safer fuel which maxes out at a ~65% power increase, regardless of whether the pellet skirt was less than 1/4th full of Crisco, or filled completely to the top. Crisco is also easier to handle over a wider temperature range than lard or similar food grade frying fats.
I'm doing this for my own entertainment as a retired thermo-mechanical/energy conversion engineer and long time airgun hobbiest. It's exactly the kind of information about break barrel dieseling which I've wondered about for 50 years since I got my first springer. I've read forums for years and always hoped that someone would test it out in enough detail to get some accurate and repeatable results. I'm just tired of waiting and finally have time and money and spare airguns to just test this for myself over the next few months.
When I get a broader set of more accurate measurements together I'll post them as a summary under a new topic heading. That's assuming that my .22 Maxxim and incoming .30 Hatsan 130s can both hold up to the strain of the repeated dieseling for at least a few hundred more test shots. I'll also be shooting for about a consistent 45fpe or 50fpe out of the ~30fpe .30 Hatsan 130s using dieseled pellets. I expect the Hatsan to hold up for more dieseled +65% power shots than the Maxxim before anything breaks. And should know for certain one way or the other before the end of this year.
JP
JP.- I really do admire your tenacity and methodical mind.
Congrats on some good work and a good writeup.
I may not agree with you, but I do think you have a fine mind.
Of course, after the praise comes the homework, LOL!
If you have the time, it would be very interesting to "soft-capture" some "dieseled" pellets and see what is happening with their shape.
Assuming that the shape has not blown out, it may be that the pellets can still retain some accuracy, and therefore the utility of the concept would be there.
Personally, I would research into some device that would feed an extruder that could create "micro-cakes" of the right weight in solid state for different calibers. That would be easier to handle than the liquid (IIUC that you are using liquid Crisco).
In any case, keep us posted!
HM
Hector, I use regular semisolid Crisco. It flows well under mild pressure out of a small blunt syringe needle and sticks to the backside of the pellet without running out. Applying the dot accurately inside of the skirt is difficult since the back of the pellet is small and even a small hand tremor makes it difficult to be consistent.
I bit the bullet today and ordered a Gilson Distriman postive-displacement repetitive pipette for the rest of my testing. It's a laboratory type hand held instrument which can handle viscous liquids, and which accurately dispenses very tiny amounts drops in varying multiples of 0.001 milliliter. I just got a very good deal on a used one and it appears to be the right tool for the job. News ones run about $500. So ultimately the actual usefulness of any Crisco volume vs power tables would depend on a person's ability to measure and cleanly dispense the amounts involved.
You'd mentioned prepared pellets, the black powder folks have used something similar for years. I don't see it happening for airguns though. Many people point out that there isn't any reason to diesel an airgun on purpose a few more fpe when there are so many more powerful guns coming along all the time. I agree with them, but I can also afford to break a few of my airguns experimenting with them.
I suppose it's sort of like the guys who load their own bullets. Ask one of them if they've ever shot any hot ++ loads in their pistol 'just to see how they'd work'. The big difference is that it is a lot safer testing 0.10 grains of Crisco in an 18gn airgun pellet, compared to testing the effects of adding a couple extra grains of smokeless power behind a 125 grain firearm bullet.
JP
What about paraffin? Might be less messy at practical temperatures. Might adhere to the pellet better. You would need to know things like the flashpoints/autoignition temps of both as well as the energy J/g of the two. I'm just guessing at this point.
Right now you are working basically, with vegetable oils. Hydrogenated to make them spreadable, but deep down they are just vegetable oils.
There are other potential candidates for this same treatment. I experimented a little with Diesel "soaps" and they work. At that point in time, I was living in a country where firearms are, basically, barred from the common person's reach.
Back then PCP's were the realm of Olympic shooters and/or very well heeled gentlemen. So again, a no go.
In the current state of affairs, I can see a "caseless" rifle that was easy to maintain, workable, reliable, durable, and powerful enough for some basic "pesting" being a useful addition to the possibilities available.
I reloaded ammo for many years, and even swaged my own bullets because the ones available would not satisfy my requirements. Currently I am slowly getting ready to go back (after more than 30 years), via the BPCR branch that seems much more challenging.
So, the idea of a "caseless" system makes sense to me. As a firearm. Fulfilling all rules and regulations. I think it is the next "big step" after almost 200 hundred years and change of brass cases.
So far, the caseless systems developed have been either too expensive to operate for any length of time (like the UCC system), or military in their orientation where durability was basically non relevant.
Your experiments seem to be laying the groundwork for this in a very good way.
Diesel "soaps" are a "pre-form" of a final fuel production in one of the methods to make bio-diesel., in another it is a side product, almost a "contaminant", and while it does have lower energy content than biodiesel itself, it still has more energy content than simple vegetable oil.
There is a vegetable oil fraction that IS solid at ambient temperature, widely available and inexpensive: Coconut oil. It also has the lowest flash-point of all vegetable oils. Palm Oil Stearin would also be interesting to research.
My guess is that Paraffin, in its solid form, will not have time to melt and combust within the short cycle of a piston rifle. but I may be wrong.
Anyway, even though by then they are no longer airguns, the fact that these instruments are fired using a compressed air piston makes them interesting in their own right when taken to their proper purpose.
JMHO
Good work and keep us posted!
HM
So, the idea of a "caseless" system makes sense to me. As a firearm. Fulfilling all rules and regulations. I think it is the next "big step" after almost 200 hundred years and change of brass cases.
So far, the caseless systems developed have been either too expensive to operate for any length of time (like the UCC system), or military in their orientation where durability was basically non relevant.
This makes some sense. Caseless ammo, flying cars, jet packs, teleportation. No, we have tablets. 🤬
For those wondering what problems case-less ammo has.
A bunch of this bleeds over into airguns, which are already caseless.
@hector-j-medina-g
Fuel inserted into a pellet skirt before firing it needs to adhere to the pellet well enough not to run out while the pellet is being loaded. I'd considered testing tiny dots of glue. It would work but any overload of the pellets would unacceptably foul the action with glue vapor. Vaseline would sag out if left in the pellets and lard was too firm to dispense correctly. Crisco (pure cotton seed oil instilled with the same Hydrogen which powers the sun! as the ads might say) just happened to have the best balance of qualities and those pellets could be preloaded into a 10 pellet Swarm magazine ahead of time without messing things up.
If there were a commercial reason to develop something like this for airguns they'd find a fuel which sticks tightly to the pellet when applied then dries into a film unaffected by normal temps. This stuff isn't all that difficult to analyze and test but it take time and money and equipment and and motivation.
And what if a small company did start offering airgun pellets with a thin film of dieseling compound already in the skirt? With a Disclaimer of course, and just enough fuel for a ~25% power increase so they can claim to be (somewhat) safer for the rifles than a DIY load. Would anyone with a break barrel rifle try them? Yes, almost everyone with a break barrel would probably try a product like that, why it certainly sounds safe enough ... I won't rehash the obvious legal problems which might result from an attempt to commercialize the production of any pellets preloaded with fuel (= bullets under the law most likely).
The Barakuda ether injection system failed because the design didn't have enough money behind it. A family member of mine worked with the emergency valves on underwater well heads, the design demands are critical and they almost never fail because they are actually designed not to fail. A Barakuda was designed to test the market for possible interest sufficient which might help to fund a better version.
It would be easy enough to place a tiny fuel orifice in the compression chamber immediately behind the pellet to force feed a tiny ~0.01ml measured amount of semisolid fuel as the gun is cocked. Very simple external control using a knob to turn a tiny internal screw pump to force feed the fuel in. No market demand for that though and it would probably be considered as a firearm anyway.
Reminds me of the PCP arena where using Helium instead of air increases shot power by 50 to 75% with no other changes to the airgun. People who never worked with Helium would always warn about guns blowing up or floating away, much too dangerous etc etc. The techie types just looked at the design of the airguns and tested it . Turned my ~12fpe FN8 .22 PCP pistol into a 22fpe barker back when there weren't any +20fpe air pistols to be had. These day plenty of folks still use Helium though prices have skyrocketed in past 20 years. Some hunters use Helium for reach, and some <12fpe folks do it just because 12fpe is such a low power limit to be stuck at all the time.
It would also be possible to add a small electric heating plug in a CO2 rifle which would flash heat the CO2 on the way past as the valve was opened. Easy double or triple power per shot, no more problems with cold weather performance sort of thing. Just no reason for it though, PCPs using air have cornered the high power as the better overall technical and commercially viable market solution.
If there is a point to my ramble it's that airguns are relatively simple to design as far as machines go, think Webb telescope for the other end of the design spectrum. But the ones we have already are quite good for general use by average folks for target shooting and light hunting. AEA's new .45 cal semiauto pistol/carbine has just about the same power output as a regular .45 cal 1911 firearm, and some PCPs already have external 15 to 100fpe power adjusters. So we're at the point where individuals usually try to just work within the design limits of what's already available.
Like for dieseling pellets. If vendors won't offer special piston seals which are intended to hold up to the extra heat and pressure pulse of intentional dieseling, then hobbiests like me just test the current designs to failure to set some parameters of future work. And maybe eventually someone sells some 'heavy duty' special air gun piston seals on eBay. I saw some advertised on an Australian web site though it didn't mention dieseling, just longer lasting or something like that.
There really should be a word limits on these posts so that people don't just ramble on indefini
WARNING * EXCEEDED WORD LIMIT * WARNING
JP
should be a word limits
Not "word" limits. There is a character limit of 5000.
You came in at 4296 characters for 758 words without the extraneous line breaks below your signoff.
And here is a Domingo Tavella paper on topic at hand: https://airgunwarriors.com/resources/library/Dieseling_in_Spring_Piston_Airguns_A_Conceptual_Analysis_Domingo_Tavella.pdf
Databases are great for stats and setting constraints like that.
If one of my coworkers asked me for help with a stuck print job, sometimes I'd tell them it might have been caused by the new grammar checker software we'd been testing on the network to help reduce our paper costs.
'You know, that new one which prevents something from printing if the grammar and spelling isn't at least at a high school level.'
It helps to insert some mild humor into serious work sometimes, it gives them something else to think about for a few minutes.
The funny thing is that the idea of us installing an automated grammar checker to police their print job didn't surprise them at all. Or that fact that something they'd written might have failed the 'printer worthy quality' test.
I worked closely with many of the same scientists for over 30 years. I'd tell them that I was joking about grammar police software after I'd fixed the real problem. But I swear that their e-mails to the office were usually a bit easier to understand for at least a few weeks after that anyway.
JP
JP.- It is my understanding, from some years of working for the vegetable oil industries, that CRISCO is now NOT made of cottonseed oil anymore.
Most vegetable oils have more or less the same caloric content and about the same flashpoint. It is once it is trans-esterized and becomes bio-diesel, when the energy content becomes interesting.
GWH.- some ideas were simply ahead of their time. Having tested the Steyr ACR, which used a polymer case, I now see that polymer cases are being actually commercialized. Which is a good idea.
The other outstanding idea that the Steyr had was the flechette round.
The way conflicts are evolving, it may be that the future lies in some sort of diesel driven gatling gun, where the projectiles are inserted and seal the bore at some point in the rotation, and then a piston, with a proper carburetor puts the energy behind it. No cases, no dead weight, time for cooling off the barrels... lots if advantages. Since the "mini-gun" is already considered portable, I think we are not too far off.
True that with the automotive valves designs we use the max pressure in a barrel is about 180 BAR's but in a good sized chunk of lead, that could mean easily 400 fps, and that is above the speed where humans can react in close quarters.
Still, it is interesting to use an airgun as a test-bench.
😉
Keep well and shoot straight!
HM
Hector, what can you track down which only has about 1/2 to 1/4 of the stored energy of lard/Crisco/Vaseline? Non-petroluem, less viscous than tooth paste over 70F, melting point over 120F, with similar sized molecular fractions to reduce the chances of getting uncombusted longer chain residues. I didn't bother to check a chemical index for better fuels since I wanted to use something inexpensive which many people would already have at home.
That's what I think we need if possible. A compound with a lower energy to volume ratio than Crisco/lard, to make it inherently safer and easier to handle than Crisco. Crisco's maximum +65% power increase in a Maxxim, due to the limited amount of compressed air used per shot, is still considerably beyond design specs. And measuring out the small amounts of Crisco (<0.05ml)needed to consistently keep the dieseled power ratio under, let's say +50%, is difficult without a special dispensing device.
But if there were a commonly available substance which would only produce a maximum power boost of about 1/2 that of Crisco, with even a full pellet skirt of it maxing out at +35% increase instead of at +65% for Crisco, then all of this would be very much easier and safer for the equipment.
If I test a much more energetic substance per volume than Crisco, no matter what warnings I might give to people not to use too much! (gin just came to mind for some reason), people are still going to fill their pellet skirts to the top with it just to see what happens. So as a public service I'd like to test some lower power-per-volume alternate to Crisco.
Something which can't exceed maybe +40% to +50% power increase per full pellet skirt.
And where the smaller amount needed for 100% combustion and max power increase would be large enough to measure out by hand. Those pellet skirts don't hold much volume. So ideally we'd have a fuel where filling a .22 18gn pellet skirt (my pellet volume reference point for testing) 'about 1/2 way full' by eye would put them close enough to the full combustion amount to prevent unburned residue.
A common product like that must already be out there of course, I'd prefer a food product which people can get in the food store. I don't feel like tracking one down or ordering a specialty product from a lab, I'm on a roll (slide?) with the Crisco at this point.
But I would be more comfortable on behalf of anyone who might ever try something like this to recommend using a fuel which is inherently limited to a +50% max power boost per shot, maybe less, instead of Crisco with its +65% power boost.
JP
I don't eat hydrogenated vegetable oils like Crisco anymore. One of my sons became alarmed when he heard that there was a can of Crisco in my house and sent me links to health warning about it. I thought that parents were supposed to send their kids health warnings, not the other way around.
Here's something else which what a person can do with an unused can of Crisco. Turns out (per YouTube) that a tub of Crisco makes a good 2 month (at 8 hours per day) emergency candle. You just stick a regular wax candle into the center of the tub and the melting Crisco feeds the flame as the candle burns down. More fuel for thought.
Why not adsorb or absorb the fuel onto solid substrate, such as the little cellulose discs made by a paper hole punch?
Followup thought... what happens if I glue a cap-gun strip-style charge in the pellet skirt? 🤣
Regarding non-petroleum fuels. Castor oil is the tackiest vegetable oil I've had the displeasure of touching, and was used as lube in 2 strokes. That was long before my time (although castor is probably still used somewhere) and I'm unable to report on the carbon fouling characteristics.
My own version of cosmoline (minus the sewage-skimate odor) is made with light petroleum oils and thickened with toilet bowl wax ring and paraffin solids. It's solid/gummy at room temp, melts suddenly around 125f, but includes oils fluid at all normal temps. Perhaps blending fuels could yield something like a double base smokeless?
Last thought, on the regularity of chain lengths. There are some apps which require non-gumming lubricants, such as aircraft control cables. I'm unaware of the base stock. Unfortunately they're usually very thin and tend to creep. They're supposed to creep (wick) and they dry up.
This is an interesting thread, quite removed from the common use for the substances in question. Fun to brainstorm anyway!
OK, this is where we diverge.
I do not see the advantage of adding power to the hands of people that won't even play safe, let alone nice.
My thinking is going the other way, where instead of a primer, you had a spring-piston driven ignition system for a fuel based firearm. But that belongs to another forum and another discussion altogether.
DIANA airguns can safely deliver 23-24 ft-lbs at the muzzle (in 0.22") as airguns (with no dieseling involved). For ME, that's enough energy to do what needs to be done with a spring-piston airgun.
If you require more, then go PCP or get a firearm.
With the current trends in PCP's I see very clearly that, soon, we will be as regulated, if not more, than firearms.
Keep well and shoot straight!
HM
Can dieseling damage the barrel of an air rifle? I can't help it but the concept of dieseling gives me an idea, that I probably shouldn't go through with.
I agree with marflow.
Neither dieseling, combustion, nor detonation of lubricant in a springer is likely to ever harm the barrel per se, apart perhaps from simple fouling.
Seals, spring, compression chamber etc., definitely yes can be harmed. But the barrel, no.
First of all, JP, thank you for sharing the detailed results of your ingenious, careful, and (very!) interesting experiments!
Then a question, please.
Is it your opinion that all combustion of the fuel you add to the pellet base is confined entirely to the breech and barrel, or can some of the fuel migrate backwards "upstream" through the transfer port into the combustion chamber to be burned there (perhaps in subsequent shots)?
If the former case holds, then this may help explain why your experience with specific aspects of the combustion process (e.g., insensitivity to the amount of fuel used) differs from that reported by others.
Fuel vapors would be extremely likely to condense in the cylinder and on the seal.
Crisco's energy density might be similar enough to gasoline, to apply internal combustion engine thinking. The stoichiometric air-fuel ratio is 14.7 parts air to 1 part fuel. Obviously JP is running excess air, aka lean.
Now back to Steve's question. How does and engine which is running lean, fail to combust all the fuel? These vapors must be escaping the flame front during piston bounce.
I'm not familiar with the piston/valve arrangement on the Gamo Swarms. I'll get to see one when I take my Maxxim apart at the end of testing to have a look around and change the piston seal.
Most unburned fuel vapor would just exit out of the barrel as vapor and smoke. Less would be deposited along the inside of the barrel as the hot compressed gases cool on the way out. And some residue would probably remain in the pressure chamber. And on the face of the piston seal as the main spring holds the piston in place at full extension until the rifle is cocked again. Not sure if there is any way that gas would be allowed to escape back past the piston to pollute other parts of the rifle. But there are an lot of different designs out there.
The Crisco's flat x1.65 power factor between 1/5th and a full pellet skirt doesn't doesn't conflict with any info about airgun pellet dieseling which I've ever seen. I spent years studying compression & combustion systems in college 40 years ago and this is very typical behavior for any oxygen limited single piston diesel engine.
Remember, this is all specified for the skirt volume in a .22 18.13gn diablo pellet, using the amount of compressed air available in a Gamo Swarm Maxxim, and using Crisco as the fuel. It required measuring volumes of <0.05ml of a semisolid.
I'd be surprised if anyone else has been testing a specific product down to this volume and power level recently. And if they have I'm curious to know how they managed to measure and dispense the tiny amounts required accurately enough to get consistent power curves. Most people just sort of filled up their pellets by eye or eye dropper, maybe a little or maybe more. And then took a few erratic readings or shot some boards and gel. All of that didn't prove anything very specific, except that dieseling can break a good rifle bang quick as that.
I understand everyone who believes that if a break barrel rifle was intended by its creator and overseas distributor to shoot at 15fpe, then by all that's natural it should not be asked for more than that! OK, well maybe a slightly stronger mainspring or a bit more pressure in the gas piston would be alright. So maybe 10% - 20% more power than stock max would be OK. But that's it, and those increases are only OK because those are natural Mods to the rifle itself, even though they are often provided by 3rd party vendors because the rifle company won't do it.
Honestly, I view the hours I'll spend on this as a public service to the air gun community. Break barrel airguns are not designed to diesel, it increases wear on them if nothing else. And break barrel airguns are relatively inexpensive, there's no good reason not to just get a 2nd one with more power instead of risking a perfectly good 15 pounder. People should not intentionally diesel their airguns trying to get more power out of them.
Certainly not based on any of the prior information which I've seen about it. It is incomplete and often misleading.
Any test results and summary information I can provide will only be a very small counterbalance to many years of inadequate testing of intentional pellet dieseling, often using inappropriate dieseling agents, and almost always using them in excessive guesstimated amounts. Maybe the power factor can be easy brought down to the +10% or +20% range, same range as more typical mechanical Mods. It's just a simple engineering question to me, people can do what they want with the results.
I've repeated my disclaimers and warnings about doing this for what they're worth. And just ordered a Crisbee puck and a Larbee puck to try. Maybe that's the ticket, never even heard of them until a few hours ago.
JP
A sufficiently lean mixture, held under enough pressure, at a high enough temperature, and held there for a sufficient length of time, and with enough available Oxygen to fully combine with the many different molecular weight compounds in the fuel, will combust completely.
If there is too much fuel available to combust completely then the reaction has not met one of the conditions listed. And I think we'd all agree that insufficient or inefficient combustion during dieseling is indicated, at least in part, by some fuel vapor and possibly combustion smoke from the barrel. And too much fuel is also indicated by the elevated velocities of dry pellets which are shot immediately after the dieseled pellets, with those velocities gradually dropping back down to normal after several dry pellets. That just means that there was residual fuel remaining in the system left over from the previous dieseled pellet.
At a fill point below about 1/5th of a pellet skirt full of Crisco, the velocity of a dry pellet shot immediately after 8 dieseled pellets dropped immediately back down to normal. Dropped back on the first shot afterward. A string of 8 dry pellets had a max velocity variation of 32f/s, compared to a string of 8 dieseled pellets which had a max velocity deviation of only 34f/s. That's exactly what I'm looking for, a sufficiently complete combustion which eliminates any residual fuel from fouling the action for the next shot.
The main problem with using Crisco is that the very tiny amounts required to force the reaction down below a +65% power would be very difficult for an average person to dispense accurately without a special tool. And the 65% power boost resulting from using much more than about 1/5 of a pellet skirt full of Crisco is releasing too much energy to be safe for the mechanism over the long run.
A few days ago I asked a materials engineer and lubrication expert I know to think about the question and try to recommend a lower energy compound than Crisco which would be easier to measure. He'll also ask his friend who runs a small company in Texas producing specialty greases. They are both hunters who had break barrel springers themselves when they were young. So they understand the situation and will try to come up with a lower energy/volume product for me to try which people haven't tested in this situation before. I'll continue to test Crisco though since it works pretty well and I'm set up for that already.
My new Hatsan .30 130s was delivered recently and is still in the box. If I get a chance this week I'll run a few similar Crisco power tests on it. The Hastan 130s has twice the average power of a Maxxim, its 50gn .30 pellets weigh over 2.5x as much as the .22 pellets I tested, and there will be more available Oxygen for combustion due to the larger volume of air being compressed.
I'm not sure yet what the results will be for that specific combination of factors but I'm really looking forward to finding out. That will provide me with some very valuable perspective on whether the results I'm getting from the .22 Maxxim can be generalized across those 2 calibers and gas piston air rifles.
My prediction is that I'll eventually find an optimum Crisco ratio of somewhat less than 0.5% of the pellet's weight, and which provides complete combustion at a ~65% power increase. And that ultimately I'll find something other than Crisco to use which has much less energy. Hopefully limited to <25% max power increase per pellet, and which is easier to dispense accurately than Crisco. I never liked studying about the energy dynamics of high pressure systems very much in college. But developing a lightweight testing protocol like this for a hobby which I enjoy so much is a lot of fun for me now.
JP
I'm not familiar with the piston/valve arrangement on the Gamo Swarms.
Sense dictates re-reading Hector's post https://airgunwarriors.com/community/postid/46932/ while looking at the diagram below.
The part labeled "nozzle" is commonly called a transfer port. Very similar to a "tortured path" method of flow regulation.
Piston spring pre-load when de-cocked is low enough that I've never needed a spring compressor, so far.
It is MHO that the OEM reciprocating parts are poorly adapted to the pressure spike generated by the addition of fuel.
Good goals here might involve...
De-stroking, aka making a shorter compression tube.
Doing the math on fuel/air ratio, and examining the behavior of a flame front among cylinder head combustion area shapes.
Designing a piston face shaped to directed the wave of fuel vapor back into the transfer port, and maybe a larger transfer port.
Additional spring preload when in the decocked position. Perhaps combined with a heavier piston, to reduce bounce.
A heavier pellet, to delay the start of movement and force peak pressure to occur later, and/or over a longer time span.
The seal is the big make/break here, and I'm at a loss.
I don't know Hector Medina but he's obviously a kindred spirit. The last few lines by him in his post at the link in your last note sums up the general situation as well as I ever could;
***********
.... We now have the knowledge to make AIR guns yield 23-24 ft-lbs without any "dieseling", simply by using basic physics.
So, IMHO, there is no NEED for it.
You can use it, at the expense of reduced life in the spring and seals.
As usual, it's up to each one to decide what they want to do with THEIR stuff.
HTH, keep well and shoot straight!
**************
My personal mini-quest here is to finally get some answers to the same airgun dieseling power questions which I've had for over 50 years now. I won't do a YouTube about the results. Just some airgun forum posts where interested google-searchers can find the info as well as the critiques and counter arguments which are likely to follow.
Within the limitations of the simple system schematic shown above, the focus would be on selecting a fuel which doesn't ignite until the piston is at full extension. It eliminates any back shock on the piston from dieseling while the piston is still moving forward. And it minimizes the space available for unburned fuel to be drawn in if the piston is briefly pushed partway back again.
And the same fuel should combust relatively slowly after ignition to produce a more spread out pressure pulse. We don't want a very abrupt, high energy high temp situation where fuel detonates as soon as the trigger is pulled and while the piston is still moving forward. That's what knocking in a car engine is, detonation before the piston reaches top dead center and it is very hard on metal parts. We want a smooth combustion instead, with less volatility, slower to ignite and burn, with less energy per volume than Crisco for ease of application.
These types of analysis can become very complicated once a company or real university lab starts adding sensors all over a test rig so get actual pressure pulse graphs. None of that is necessary in this situation where I'm only measuring a few different different fuel and pellet weights, and then using a chrony to check the results. The end results are what count for most people, not so much the exact internal energy flux over time.
This thread is getting unwieldy now because I'm such a long-winded writer.
It's going to take me weeks to test a variety of things before deciding how to present some summary info. I'll do some basic Crisco power checks with the .30 Hatsan 130 within the next few days and then post those numbers as a comparison the preliminary numbers I got with the .22 pellets.
That will be a good point for me to stop posting on this old discussion thread. I'll eventually start a new thread over in break barrel territory which has a better summary of what I've found to that point.
I'd mentioned about it being difficult to accurately measure the small amounts of Crisco I'd used. Here's an example.
One of those little lines on the penny below is approximately the volume of Crisco which provides a relatively efficient +65% power increase to an 18.13 gn pellet shot out of my Gamo Maxxim gas piston break barrel rifle. I was careful measuring the amounts, but it still looks like there might be a 10% volume difference between them.
Now, it might only take 1/4 of one of those little noodles of Crisco to keep the power ratio down around +25%. I'll check that eventually but it's already easy to see that Crisco has too much energy per volume to be used both safely and easily for dieseling pellets.
JP
Fuel vapors would be extremely likely to condense in the cylinder and on the seal.
Crisco's energy density might be similar enough to gasoline, to apply internal combustion engine thinking. The stoichiometric air-fuel ratio is 14.7 parts air to 1 part fuel. Obviously JP is running excess air, aka lean.
Now back to Steve's question. How does and engine which is running lean, fail to combust all the fuel? These vapors must be escaping the flame front during piston bounce.
Well, a typical springer stroke volume is about 50cc = ~60mg = ~1gr of air. Taking the 14.7:1 air/fuel ratio for complete combustion would limit the amount of fuel to only 1gr/14.7 = 0.07gr = 47% more than the 0.1gr of grease JP says his ...
...simple DIY device which can dispense Crisco fairly accurately in increments of about 0.020ml or ~0.10 grains.
...can accurately dispense with just 1/4 turn of the metering screw.
Which implies he's actually running at least 47% rich with just one "noodle," thus consuming all the O2 rather than all the fuel, and perhaps explains very simply why more fuel produces no more ME.
That's what knocking in a car engine is, detonation before the piston reaches top dead center and it is very hard on metal parts. We want a smooth combustion instead, with less volatility, slower to ignite and burn, with less energy per volume than Crisco for ease of application.
The knocking in a piston engine is usually a failed sleeve bearing at the large end of a connecting rod.
"Spark knock", ping, pre-ignition, or detonation, can be caused by a few things. Overtemp conditions are the most insidious.
Sufficient detonation results in closure of the top ring groove, and a stuck ring. The rest is NSFW.
Looking at Steve's math, it's worth noting that the nominal range for air/fuel ratio runs from 8:1 to 18.5:1.
It's an interesting thread. I think you're in for a good time shooting the 130.
...
Looking at Steve's math, it's worth noting that the nominal range for air/fuel ratio runs from 8:1 to 18.5:1.
And just to tie it up with a bow, sez here the formula for Crisco is: C21H42O5
So out of the tub, it's already 79/84 = 6% oxidized.
Quick initial results for the Hatsan 130s in 30 cal with a Vortex Strike 48.60 grain pellet:
5 dry pellets: 537f/s - 31.1fpe - Baseline
4 full pellets: 706f/s - 52.7fpe - power increase x1.69
5 pellets ~0.2ml (about twice what I'd tested in the .22 pellets): 746f/s - 60.0fpe - power increase x1.93
Interesting result that a pellet skirt full of Crisco produced a less powerful shot than using the smaller ~0.2ml amount.
The smaller amount of Crisco was still a bit too much since it still produced a small amount of smoke/vapor which lingered in the barrel. So I blew lightly into the barrel to clear it out before loading the next pellet. The velocity of a dry pellet dropped back down to normal on the 1st dry pellet shot after the 0.2ml dieseled pellets. So it's getting close to full combustion at this point, with a 93% increase in fpe per shot.
Velocities for ~0.2ml in the 48.60 grain pellet varied by max of 42f/s (or by 30f/s if one shot ignored), compared to max variation of only ~15f/s for 10 dry and relatively inexpensive .30 Hatsan Vortex Strike pellets. Another indication that even that small amount of fuel was a bit too much. Though a moderate variation in velocity doesn't matter much at shorter ranges, and coule be reduce by weighing/sorting pellets first like the bench rest folks. By comparison, the max f/s variation on a similar string of dry 18.13gn .22 pellets out of my 22 Maxxim was 32f/s).
Here again, using even a very small amount of Crisco dabbed into a .30 pellet by hand and measured by eye, you'd still increase the power/shot by about 90%. That's much too hot a shot in my opinion.
I'll try to wrap up my comments now as my last post in this old discussion thread. Now that I have a better focus and some preliminary results I'll spend the next weeks trying some other variations. The Gilson Distriman repeater pipette can accurately dispense the very tiny amounts of Crisco needed to keep the power increase in the 25% range. But a lab instrument like that is expensive. So only a few retired techie types like myself with time and (apparently with) money to burn are likely to bother with anything like that. I've been improving my DIY version of a micro-dispenser as well and will include that in my future posts in a new discussion thread.
There are also a few additional products headed my way for quick full-pellet tests.
No idea how any of them will compare to the Crisco for dieseling. Or if their consistency would allow them to be dispensed in the correct without heating them first. But I'm planning to find out:
Crisbee (Soybean oil, beeswax and palm oil)
Larbee (Lard and beeswax)
Shea butter (Shea nut extract)
Primal Fat Coconut Ghee (Clarified butter and coconut oil)
Thank you all for your comments they have helped.
JP
Good Job!
I guess I need to look into the Hatsan's architecture, and recover my notes from the old Mendoza experiment.
In the old days there was the concept of a "Rook Rifle", usually "small bores" (in those days that meant a 0.30"-0.32" cal). We may not be too far from the idea.
🙂
Thanks for your perseverance, and keep us posted!
HM
Crisbee (Soybean oil, beeswax and palm oil)
Larbee (Lard and beeswax)
Shea butter (Shea nut extract)
Primal Fat Coconut Ghee (Clarified butter and coconut oil)
Cocoa butter is similar to beeswax in hardness, dry, less tacky, carnuba-esque? Slower to melt than paraffin, smaller crystals.
You'll find raw shea to act a bit like a low melting point canning paraffin, but without the uniformity, shea can include a range. This can be stratified by melting in a tall jar. Some might be near liquid at room temp, others very solid. Break the jar to extract? The hardest stuff will give you metering problems. You could attempt to blend while cooling to improve flow?
The "Primal Fat Coconut Ghee" sounds like something for people who only know how to use things according to the marketing. If it's made with common coconut oil, this one will likely have a melting point too close to room temp. Prize awarded for all out fire and heavy charge performance, but fail on temp stability.
Crisbee and Lardbee will result in sooting, in all but the lightest charges. Lardbee is my new official compound for smoking bullet molds 🤣 🤣 🤣 Start low, consider using a chad to reduce charge weight further. Gonna look like the Civil War at max.
My predictions, because brainstorming is fun.
A paper hole punch measures 0.27" (mine anyway) Does the chad fit inside a .30 skirt? If so, cut the hard stuff back with mineral spirits or thinner of your choice. Dip, dry, weigh. With this technique, you could also test canning paraffin, without fussing over dispensing.
I can already see a tool for this, a special .177 paper punch. Nice... but not today internet.
edit after reading Steve's post... shower thought... nitrated chads?
You guys are great, I knew that I wouldn't be the only one interested in a closer look at how a more controlled dieseling process affects performance. I still want to leave this thread after these couple of follow-on posts, and have a more thorough discussion later on when/if I have better info.
First another short update on the Hatsan.
I loaded some 48.60 gn .30 pellets with approximately the same ~0.1ml amount of Crisco which had been used in testing the 18.13 gn .22 pellets in a Maxxim. These are approximate volumes used, the pictures will help for perspective on the sizes. Shown here next to, and inside of a .30 pellet.
Next tried some pellets using about one half of that amount (~0.05ml?), hoping to get on the lean side of the mix and thereby reduce the % power increase.
Hatsan Vortex Strike 48.6gn 30 pellets
Dry pellet: Avg 521/29.3fpe
~0.1ml Crisco: Avg 698/52.6 Power Increase x1.79
~0.05ml Crisco: Avg 678/49.6 Power Increase x1.63
Power probably continues to drop when less than 0.05ml is used. Even ~0.05ml is too much though at 63% power increase and because it generated a couple of small but impressive spouts of flame. Velocity of the first dry pellet fired afterward was back down to average.
So it looks to me like Crisco has too much energy to be used safely to diesel pellets in the .30 Hastan 130s gas piston break barrel rifle. And although technically possible, it would be very difficult or overly expensive to dispense it accurately in the very tiny amounts which would be required for safety.
I'll wrap up with a short description of the updated DIY small volume dispenser which I used in my next post -->
Bullocks. Serial dilution will get you down to mcg levels with 2nd Grade math, dilutant and pipettes.
mumbles in metric...
To dispense the amounts shown in the previous post, I cut a slot in a small board which was wide and deep enough to hold a disposable 1ml lubrication syringe in place with blunt needle extended past one end of the board. Then glued a 1/4" nut into one end of the slot in the wood, and threaded a 1/4x20x4" bolt through the nut. Twisting the bolt slowly depresses the plunger.
You would need a little milligram scale with a draft hood to accurately check those small amounts by weight. This DIY Crisco dispensing device only provides a rough approximation of the tiny volumes being dispensed.
In fact, at the lowest amounts dispensed, it was more consistent to just use the length of the hanging noodle of Crisco from the grey 16 gauge (1.2mm ID) needle, and not the amount of turns on the bolt. A noodle of Crisco about 1/4 inch long (~6mm) should have a volume of about 0.0068 ml, but I won't be really sure until I can weigh some of them more accurately.
I made a holder for the dispenser from a 2x4 and used Velcro so I could position the height of the dispensing needle correctly. And after dropping quite a few pellets I finally drilled a few shallow holes in a small board to help hold them while being filled.
The device worked within it's obvious limitations. It was not accurate enough to consistently dispense the very small amounts of undiluted Crisco which would be required to keep the power increase due to dieseling within the +20% to +25% range. That may partly explain why accurate laboratory grade dispensers for viscous compounds in this <0.01ml range volume range usually cost several hundred dollars.
My results so far should help to dissuade people from just randomly filling their pellet skirts with different kinds of fuels 'just to see what happens'. All of the power increases I've seen were too much for continued use in either of the rifles tested, and ran a serious risk of eventually damaging the soft piston seal. Even when using only the smallest amounts of Crisco shown above,
The Hatsan compresses more air at a higher pressure than the Maxxim does. That difference allowed each shot in the Hatsan to consume about twice as Crisco as the Maxxim could use. So the maximum power increase in the .30 Hatsan went up to about +93%, compared with a max power increase of about +65% in the .22 Maxxim. And it is almost impossible to accurately measure out amounts of Crisco or similar semisolid fats small enough to keep the power increase in much lower and safer power ranges.
So if you have never tried to diesel a break barrel rifle on purpose before to get more power out of it, this explains why you should not do it. There isn't any easily practical way for the average person using Crisco to control the power increase down to a level which is safe for the rifle. All you'll probably do is to damage a perfectly good air rifle for no particularly good reason. Just pick up a good deal on a used high-power break barrel in the Classifieds and use that one for the hot shots instead.
later
JP
Suitable solvents can dissolve most uniform substances into as dilute a solution as needed, just like the tiny amount of gold which is dissolved in seawater. Eventually serial dilution leads all the way to homeopathic medicines.
Unfortunately Crisco only dissolves in non-polar solvents. I considered using acetone at maybe 5:1 or 10:1 but it would mostly fill the pellet skirt and need to held upright until the Crisco resolidified. Also runs the risk of incomplete evaporation of the acetone adding energy to the reaction. Could heat the pellets to dry them of course but that's too much work.
All of that would be typical work in a lab environment with solvents and calibrated glassware and fume hoods. I consider the required level of dilution and sample control in this situation to be beyond the level of the average break barrel owner. That's as good a reason as any to dissuade the average person from trying it.
I need to put this topic to rest for awhile and get back to some other dangling projects.
JP
nah, just spit on the muthaf***er, it don’t cost anything!
absolute, untarnished, ignorance!
...it is almost impossible to accurately measure out amounts of Crisco or similar semisolid fats small enough to keep the power increase in much lower and safer power ranges.
Well, at the risk of displaying more "absolute, untarnished, ignorance," what about the old maxim about lowering rivers when raising bridges is inconvenient? To rephrase to fit the current context, if we can't adequately/accurately limit the fuel supply to keep the energy of the shot to safe levels, how about reducing the oxidizer supply to more easily achieve the same objective?
Earlier in this thread I shared some stoichiometric arithmetic..
https://airgunwarriors.com/community/airgun-talk/dieseling/#post-54508
...suggesting the factor controlling shot energy may not be the volume of fuel, but rather the volume of oxygen provided by the gun's stroke.
If so, why not reduce shot energy to safe levels by reducing stroke volume -- e.g. by de-stroking the piston or sleeving the compression chamber?
As added accuracy-enhancing benefits, the former might have a helpful effect on locktime, the latter on recoil.
I was surprised to see any additional posts on this old thread. After additional testing, I determined that raw Linseed oil in amounts of ~6ul per pellet was the only one of ~ 20 potential dieseling fuels I tested which had the multiple characteristics need for predictable energy increase without burning out the face of the piston seals. The power increases were relatively modest, on the order of 50% to 90% more power per shot, the amount of increase primarily depending on the caliber and pellet type. The raw Linseed oil can be easily dispensed in the exact drop size required using a lubricating syringe and it adheres to the pellet so it won't run out of the pellet when handled.
I wrapped up my tests earlier this year by comparing the results of 4 Hatsan Model 130 break barrel rifles in 177, 22, 25 and 30 caliber. When dieseled, the better performing pellets in the 25 cal were shooting in the ~40fpe range. And in the 30 cal, which normally averaged around 27fpe per shot, went up to the ~50fpe range when dieseled. I am hoping to find the time to post a summary on those final comparisons before the end of the year.
The main points I want to convey here is that accidental or intentional dieseling of airguns for increased power using any kind of petroleum based products (oil, grease, WD40 etc) will likely damage your piston seals in short order due to the high heat and shock of combustion. I have never seen a YouTube video on dieseling airguns which even came close to providing sensible or safe (for the health of the airgun) advice. Just the opposite, those videos are actually recommending ways to generate wildly varying levels of power increase by the use of too much of inappropriate dieseling agents.
Like a lot of things in life, dieseling your airguns on purpose to increase the shot power is not recommended. And if a person were determined to do it anyway, they would be getting uniformly bad advice on what to do if they followed the various YouTube videos about it. Bad advice like 'add a drop of oil or smear some Vaseline into the rear of the pellet to make to go faster' has ruined many fine airguns over the years. I've already gotten rid of the 14 break barrels I used for the dieseling tests last year and may never cock another break barrel rifle again. At least the main info and power-curve spreadsheets are already out there on a couple of forums, though I doubt that the newbies who actually need info like that are going to find it. They'll probably just check YouTube and believe whatever they hear there.
JP
