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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 3 years ago
Posts: 513
September 16, 2020 12:30:24  

https://www.altaros.cz/en/domu/140-turned-lead-bullets-atp-55mm-22.html  

 

Let me know and we can try to organize something.

 

😉

 

 

 

 

 

 

HM


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Johninma
(@johninma)
Joined: 3 years ago
Posts: 84
September 16, 2020 18:04:02  

8 boxes comes to $173.09 US. What are you thinking?


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Doug Wall
(@doug-wall)
Joined: 3 years ago
Posts: 151
September 17, 2020 09:32:20  

What would be the hold over for that??? If I'm calculating anywhere near correctly, they are talking 400 clicks at 300M. With 1/4 min clicks, that would be 100 min, or close to 100 inches at 100 yds, or 1000 inches at 1000 yards, or about 83 feet of holdover. Have fun!


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Hector J Medina G
(@hector-j-medina-g)
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Joined: 3 years ago
Posts: 513
September 17, 2020 18:51:13  

@johninma

The real kicker are the inspection costs on the Euro side and the shipping of "hazardous materials" on the freight side.

Since the offering is for a sample pack, the idea would be to get together as many friends as possible and get the samplers here at the least "added costs" possible.

EG, if we get 8 packs together, we would be paying in total about $189 with the freight and the inspection costs, that means $23.62 per sample pack of 150 units, or less than 0.16 ea.

Once we know which diameter works best in each airgun, each shooter can decide what to order and how many.

We would make all numbers transparent to everyone.

Assuming that once we all know which diameter to order and we get 10/100 packs, then the total outlay would be about $174, or $17.40 per pack, or 0.17 per shot.

I KNOW it is about twice the cost of NSA's corresponding weight/caliber. Whether the increased BC is worth it or not, will depend on each shooter to decide.

Keep well and shoot straight!

 

 

 

 

 

HM


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Hector J Medina G
(@hector-j-medina-g)
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Joined: 3 years ago
Posts: 513
September 17, 2020 18:53:21  
Posted by: @doug-wall

What would be the hold over for that??? If I'm calculating anywhere near correctly, they are talking 400 clicks at 300M. With 1/4 min clicks, that would be 100 min, or close to 100 inches at 100 yds, or 1000 inches at 1000 yards, or about 83 feet of holdover. Have fun!

Did you note the additional objective accessory in the scope?

You take it out and you're back to a 40-60 yard zero.

There are many ways to skin a cat.

😉

 

 

 

 

 

 

HM


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JungleShooter
(@jungleshooter)
Joined: 2 years ago
Posts: 161
September 18, 2020 01:23:01  

Hector,

you're a good guy.  If I had a gun that has enough power for a 30 grainer, I'd be on that order list...!!  😀 

Thanks for looking out for your fellow airgunners!

Matthias


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Doug Wall
(@doug-wall)
Joined: 3 years ago
Posts: 151
September 18, 2020 09:00:46  
Posted by: @hector-j-medina-g
Posted by: @doug-wall

What would be the hold over for that??? If I'm calculating anywhere near correctly, they are talking 400 clicks at 300M. With 1/4 min clicks, that would be 100 min, or close to 100 inches at 100 yds, or 1000 inches at 1000 yards, or about 83 feet of holdover. Have fun!

Did you note the additional objective accessory in the scope?

You take it out and you're back to a 40-60 yard zero.

There are many ways to skin a cat.

 

 

 

 

HM

I hadn't seen the video before. It looks like it's about a 10 degree offset. We're talking about artillery aiming with that thing!


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 3 years ago
Posts: 513
September 18, 2020 09:13:57  

@doug-wall

In a way, yes. What's interesting is that you ALSO get artillery style precision.

If you think about it, it is not too different from the BPCR style of ballistics. Ondrej has not tried the Vernier tang sight like the old "Buffalo" guns use, but for all the ballistics and MV's, it should be an interesting challenge.

It's been 40 years since I shot small/medium bores at a 1,000 yards, hmmm . . .  I wonder if . . . 

 

😉

 

Keep well  and shoot straight!

 

 

 

HM


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 3 years ago
Posts: 513
September 18, 2020 09:20:43  

@jungleshooter

Matthias;

Thanks for your kind words. If WE don't look out for each other, then WHO will? The politicians?  ROFL!

Getting serious, though, the interesting thing about this design is that it is quite effective, EVEN down to 40 J (30 ft-lbs), so it's not like you need a dual tank FX or HATSAN, or TEXAN, or REX, to use them, MANY well tuned airguns with the proper barrel, can reach this power level.

I THOUGHT you DID have a few rifles capable of 30 ft-lbs in 0.22"

Let me know.

 

 

 

 

 

HM


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JungleShooter
(@jungleshooter)
Joined: 2 years ago
Posts: 161
September 18, 2020 10:36:42  
Posted by: @hector-j-medina-g

@jungleshooter

Matthias;

I THOUGHT you DID have a few rifles capable of 30 ft-lbs in 0.22"

Let me know.

HM

 

You remember right, Hector. 👍🏼

I might want to try this just for fun! 😄 I'm surrounded by dreary deserted desert hills, I should be able to find a suitable range...

Fom unsuspecting neighbors I have collected a good number of pots and pans that aren't quite suitable to cooking soup and eggs anymore, but certainly are up to the task when I want to "ring steel".... 😄

 

 

🔶 CALCULATIONS

I just did a quick performance calc. to see how different projectiles compensate for the different shooting gremlins:

How much would my POI be affected by a ranging error of 1y (=RE) and a wind estimation error of 2mph (=WE) (I'd consider both to be almost unavoidable).

🔶 POI Error at 100 yards:

🔸JSB Dm (16gr, BC 0.030):

     RE ➔ 0.35" = 0.9cm

     WE ➔ 3.1" = 7.9cm

🔸NSA Slug 17.5 (BC 0.060):

     RE ➔ 0.28" = 0.7cm

     WE ➔ 1.5" = 3.9cm

🔸Altaros Slug (31gr, BC 0.130)

     RE ➔ 0.43" = 1.1cm

     WE ➔ 0.8" = 2.0cm

 

 

🔶 POI Error at 150 yards:

🔸JSB Dm (16gr, BC 0.030):

     RE ➔ 0.71" = 1.8cm

     WE ➔ 7.1" = 18.1cm

🔸NSA Slug 17.5 (BC 0.060):

     RE ➔ 0.51" = 1.3cm

     WE ➔ 3.5" = 8.8cm

🔸Altaros Slug (31gr, BC 0.150)

     RE ➔ 0.71" = 1.8cm

     WE ➔ 1.85" = 4.7cm

*(Yeah, I reduced the BCs to more realistic values than those published by the mfctrs.)

 

Well, if the precision of these three projectiles is the same (and only IF) — then at those ranges the slugs clearly are ahead of the pellet.

The Altaros is very much ahead in terms of wind drift resistance. Yet the lowly 17.5 NSA slug (because of it's light weight) still wins at both ranges for flattest trajectory (meaning it will be less affected by ranging errors).

 

 


 

 

However, the only barrel available to me is a regular choked LW with 17.5" twist rate.... ➔ ? 🤔

If you think that might work (no promises, of course) — then put me down on your list! 👍🏼

Matthias

 


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Hector J Medina G
(@hector-j-medina-g)
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Joined: 3 years ago
Posts: 513
September 18, 2020 11:33:55  

@jungleshooter

Matthias;

I know that Ondrej tested the slugs in L-W barrels, so, as long as yours is a standard barrel, I have no reason to suspect that they will not "work", perhaps they will not be the best (each barrel has its own preferences), but they should "work".

Anyway, let's see if someone else is interested. . . 

 

 

HM


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Miles_M
(@miles_m)
Joined: 3 years ago
Posts: 48
September 20, 2020 08:47:17  

Be interesting to know where the BC figure came from, testing, calculated or guessed? The shape is very similar to the ones I was designing and testing back in 1990.

image

They weighed 14.5 grains for a BC of .057 at around 580 ft/sec compared to the 900+ft/sec for these. The G1 law is not really a suitable reference drag law for this shape so it is possible that at higher speeds the BC could increase compared to the lower speeds.


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Hector J Medina G
(@hector-j-medina-g)
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Joined: 3 years ago
Posts: 513
September 21, 2020 11:04:10  

@miles_m

Interesting Miles!

For a while, 20 years ago, I was shooting BACKWARDS some 25 grs.  0.177" cast sptizer bullets, we used to call them the "Vipers". I still have the mold somewhere. At above 680 fps they would de-stabilize from a 1/16" twist barrel. When shot in a 1/8'"  they shot beautifully at up to 900 fps which was the highest I could go with air in that gun.

The BC was something like 0.25.

In the end, sound ballistic principles are like evolutionary laws, they make all end-products arrive to more or less the same shape to accomplish the same functions.

I assume yours was a 0.22" and was made with a lead "belt" and then some lighter material injection molded into it? That would indeed be an interesting solution.

Coming forwards 20 years in my case and 30 years in yours is that CNC machining / robotics have come down in price enough to actually MAKE each one in a specially modified lathe. And that opens the possibilities in MANY ways without compromising dimensional control, nor quality of material used. Tolerances that can be maintained are amazing, and the resulting uniformity, concentricity, and homogeneity, bode well for precision and accuracy.

As for BC's, well, we're convinced that even the GL model is not the best to use for trajectory calculations of this type of projectile, besides, published numbers need to be based on G1 because otherwise people would get wrong ideas. I have not found too many shooters that understand the reality that even the standard projectiles for one drag function might have very low BC under a different drag function.

Furthermore, as we have both found from our efforts is that the industry is not really concerned with educating the public. They are more interested in high BC's (G1) that will "sell" better their wares.

I am sure that you are familiar with the many tests by independent testers that "show" that under about 1,400 fps all the drag functions are pretty much the same (of course they are not, but it is not a MAIN area of interest), and in most formal applications, they are MADE identical.

Since it is somewhat hard to achieve a trans/super sonic MV from air guns, I think that using something like the Pejsa approach will yield better results for trajectory calculations.

When I get a sample pack, I will post something. You have my E-Addy, feel free to write.

Keep well and shoot straight!

 

 

 

 

 

 

 

HM


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JungleShooter
(@jungleshooter)
Joined: 2 years ago
Posts: 161
September 21, 2020 11:26:12  

Ouuuw, yeah, different drag models, I conveniently forgot about that —

and before I got caught up into the slug craze this wasn't even an issue.... —

and now you have me wondering....

 

🔶 (1)

If a manufacturer (or an independent tester) publishes a BC in G1 — should I then set my ballistic calculator (Strelok Pro and ChairGun) to that drag model?

Or should I try to convert the G1 BC to a different drag model and use that model in the ballistic calculator?

 

🔶 (2) 

Which drag model would be more suitable to the recent .22 slugs from NSA, H&N, JSB, FX, and the smaller outfits?

My ballistic calculators give me the choice of:

GA  |  G1  |  GL  |  RA4  |  G7  |  G8  |  GS  |  GC

 

Matthias

 


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Hector J Medina G
(@hector-j-medina-g)
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Joined: 3 years ago
Posts: 513
September 21, 2020 14:58:20  

@jungleshooter

Matthias, it all depends what you want to do with the slug/gun combination.

At subsonic velocities, all models are pretty much the same.

And they don't make too much difference unless you are pushing the distance (beyond 450 meters in PB's, about 75 meters in Airguns).

TEST. Never argue with reality. Adjust software and tables to what works.

JMHO

 

 

 

 

 

HM


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JungleShooter
(@jungleshooter)
Joined: 2 years ago
Posts: 161
September 21, 2020 15:47:00  

Yeah, pushing the envelope, that is the sort of thing I enjoy, in different fields.... 😄

 

 

So yeah, more than 75y range is definitely on:

I haven't figured out just WHAT is so exceedingly fascinating about shooting long range 😄

maybe the numbers game — that at the end of a long string of numbers you get a first-shot hit:

 

(1) Figure out the MV for suitable projectiles with a chrono.

(2) Figure out the BC for suitable projectiles, using BC tables based on tests and eventually my own BC measurements. 

(3) Figure out the range to target with a range finder.

(4) Figure out the wind speed and direction with an anemometer.

(5) Figure out the impact velocity necessary for hollow point expansion using results from expansion tests, and decide on a projectile.

(6) Punch the numbers into Strelok.

(7) Dial the numbers on the scope turrets.

(8) Pull the trigger.

First shot hit!

And the quarry had no idea what hit them, nor from where!

GRIN!! 😊

(For shooting paper it's the same, just without no. 5.)

 

 

Matthias


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Miles_M
(@miles_m)
Joined: 3 years ago
Posts: 48
September 21, 2020 17:29:02  

As said most drag laws are similar at low Mach numbers but they will tend to diverge as they approach 1116.5 ft/sec so if you are using high Mvs, particularly with boat tail projectiles then you really need a boat tail drag law if you are to avoid multiple BCs for different ranges. If you are using any published BC it is always necessary to know what drag law was used particularly at long ranges for accurate modelling.

In the end it depends on how accurate you want to be in your modelling but remember there are other things apart from the drag law which will affect the accuracy of the predicted trajectory.


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