Pass through vs energy dump  

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Jacob W Sumner
(@jacob-sumner)
Joined: 12 months ago
Posts: 21
2019-01-05 00:40:04  

 

Correct me if I am wrong. But this video helps explain some of the reason a projectile that dumps all energy on impact. Is more efficient for hunting than a round that passes through

With a pass through, the high pressure would create a cavity but then the low pressure would have a counter effect. Leaving a small wound channel.

As with a full energy dump for lack of a better word. Would leave close to the same sized cavity created by the high pressure. 

I would like to hear some more opinions on this subject.

Hope everyone is enjoying their new year so far. Hope to see you on the ranges.


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TimR
 TimR
(@timr)
Joined: 7 months ago
Posts: 23
2019-01-05 07:21:02  

Good video but I don't agree.

My apologies if hunting talk is not appropriate for this board.  I'm new here though I'd been on the Yellow for decades.

At any rate, I have two thoughts.

The speed of sound is domain specific.  A pellet may exceed the speed of sound in air, but the speed of sound in water (and flesh is mostly water) is probably 20 times higher.  I looked it up last time we had this argument but I don't remember.  No way a pellet is supersonic inside anything but air.

Secondly, and I don't claim expertise here, just thinking this through, it seems to me that if it takes 4 foot pounds of energy to achieve a pass through, based on the shear strength of the material times the surface area of the cylinder sheared, then it always will.  Hit it with a 10 foot pound projectile, it will dump 4 foot pounds inside and 6 more on the hillside.  Or 60 more on the hillside if you hit it that hard.  You will never dump more than 4 unless the extra energy goes to deform the projectile and results in a larger surface area to the channel.  

Caveat:  I no longer hunt, and almost all my hunting has been at 12 foot pound level or lower.  


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Doug Wall
(@doug-wall)
Joined: 1 year ago
Posts: 103
2019-01-05 07:33:06  

I don't really think that there's anything there to go towards the direction that you want to go. Thr pass through factor is all about the amount of energy ending up in the target. If I shoot at a plastic bottle full of water with a 20 FPE .22 gun, and a round nosed pellet, it will pass right through without moving the bottle much. In that case, a lot of the energy is still retained in the pellet. If I shoot at the same type of bottle with a .40 gun, with that same 20 FPE, the velocity might be low enough that it wouldn't penetrate both sided of the bottle. In that case, the bottle will go flying, because all of the energy has been dumped into the  target. Same thing for critters.


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Jacob W Sumner
(@jacob-sumner)
Joined: 12 months ago
Posts: 21
2019-01-05 09:36:05  

Sorry for posting in the wrong spot. Thank you for moving it.

 


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Hector J Medina G
(@hector-j-medina-g)
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Posts: 243
2019-01-05 19:12:21  

Jacob,

If you really want to look into the terminal ballistics of pellets, you need to get acquainted with materials that really and truly replicate the behavior of live tissue, with its mixed characteristics.

A brief introduction to this can be found here:

https://www.ctcustomairguns.com/hectors-airgun-blog/the-universal-pellet-is-here  

My experience is that the pellets that stay in the target do the job faster.

To the point that when hunting pigeons inside old Churches I preferred a 0.25" cal. Pump up yielding barely 16 ft-lbs, but wickedly accurate with H&N Spitzkugeln over much more powerful 0.20" and 0.22" PCP's.

Unless you can find a way to drive your pellets at ~2,000 fps you won't see hydrostatic shock. And the elasticity of the medium will define the size of the permanent cavity and therefore the wound channel.

Within the realm of normal airguns, precision and accuracy of the shot are all that matters.

HTH

 

HM


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pistolero
(@pistolero)
Joined: 1 year ago
Posts: 307
2019-01-05 23:55:00  

The techno-babble of proclaimed 'experts' attempting to draw airgun hunting-related terminal-ballistics conclusions by shooting such hilariously dissimilar (to live tissue) materials as two-by-fours and/or wet newspaper not only made me ROFLMA, but provided the final impetus to write my first airgun book. I see not much has changed in the ensuing two decades (and four books). Rather, I should say some experts have managed to stray even farther outside the bounds of reality (as pertains hilarious materials used for terminal ballistics testing to draw comparisons to projectile performance in living tissue, bone, etc.). Aluminum foil? PLEASE!

All techno-babble aside, I've witnessed far too many examples of game dropping to modest-energy projectiles stopping under the offside hide (as in almost all cases), and far too many examples of game NOT dropping to much more powerful projectiles zipping right through (also in almost all cases), to not believe there is GREAT value in complete energy dump. Matter of fact the only advantage I see in full penetration is having a second hole to pass blood, for a better blood-trail (in some cases) to track that animal that tore off in a panicked sprint.

BTW, everything I just wrote pertains to chest-shot game. Brain-shot game cares not one iota about complete pass-through.

FWIW, this is not theory or conjecture; rather, VAST experience(s).

This cottontail dropped instantly to full energy-dump at 35 yards from a 5 foot-pound .22 Co2 pistol.

35 yard bunny

Shot a 42 yards with a 20 foot-pound .22 PCP, this cottontail didn't seem to care about complete pass-through... of its brain! It dropped instantly too.

42 yd AR6 #2

 

 

 

"No brag; just fact."- Will Sonnett


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Jacob W Sumner
(@jacob-sumner)
Joined: 12 months ago
Posts: 21
2019-01-06 01:42:11  

So we are clear the video is not mine and the foil is funny to me as well. Poor video choice probably but I will stick to my guns. 

Brain shots = dead aside I should have stated. A pass through with a high velocity round should leave a smaller wound channel. And in many cases, the wound channel all but closes and does not bleed near as much as one would expect. 

As with a round that dumps all of its energy, creates a gaping wound that bleeds.  Causing quicker expulsion of the target. A hollow point can still pass through retaining some energy but will dump most on impact. 

So the foil video is cool, and shows the round does have an affect just by pressure waves. But I understand there is no connection now to wound size in our small rounds.

After initial posting and reading some responses. I have been studying and having conversations with a military sniper. Sorry but I will take his expertise no offense to anyone. 

Hydrostatic shock is a miss understanding of damage caused by initial shock of round impact. is how he explained it best. Hours of online research seems to correlate. 

He used the 9x19 parabellum vs .45 acp as an example here. the .45 Acp hp stopped inside, the 9x19 hp passed through but it dumped on entry. Causing impressive stopping power. The .45 was massive damage of course. Same calibers now with solid rounds both passed through with .45 having more impact damage do to kinetic energy on impact.

The Hp's caused more damage across the board because on impact they expand and create a larger shock wave. While both solid rounds made a clean pass through dumping energy on backstop. This was tested in sub and supersonic rounds. All subsonic rounds tested stopped inside target and did more damage than a pass through solid round.

But then he went on to say things do happen sometimes that he does think are hydrostatic shock related. He used a .50 bmg as an example. The round only expands so much. But the cavity created on impact is larger than a mans torso. Now is that hydrostatic shock or impact shock? 


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Hector J Medina G
(@hector-j-medina-g)
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2019-01-06 08:25:06  

@ Ron.- I am glad I could cause some mirth in your life, though I do hope you have found a way to re-attach your rear end. It's necessary some times.

I am glad we agree that for "chest" shots at small game, pellets that stay inside do a faster and better job, and I apologize if I did not make myself clear about the use of wet newsprint. After almost 20 years of using the medium to accurately predict how a pellet will behave in live tissue it's become a given for me. And I don't question reality. Side by side testing in real game and wet newspaper (when properly configured for the shot you want to simulate)  give exactly the same results (in the pellet)  as far as terminal diameter, terminal length,  stability inside the wound channel (lack of tumbling) and length of penetration in muscle tissue.

Do note that the idea is to replicate the effect of muscle and bone (inserted into the wet newspaper) on the projectile in order to establish the critical speed at which projectiles no longer perform as HP's

Once the performance of a pellet can be established, then you can take better shots at game (always taking care of shot placement).

For the rest of the readers:

I would just like to add and make it clear that this methodology was devised, tested MANY times, and agreed upon by a group of airgun hunters with an accumulated experience of over 100 years. For those that are relatively new to airgun hunting names like Tom Anderson, Mike Pearson, or "Proff Hoff", may mean nothing, but these gents were hunting with airguns way before some of us were born. All of them now are in the happy hunting grounds.

WAY before "Syndavers" were in vogue/for sale, or "ballistic testing medium" became a commercial product, real life testing showed that the  wet newsprint method was more than suitable for purpose, and that purpose was establishing which pellets truly expanded and worked at airgun speeds, and which ones didn't.

Lastly, consider this:

The percentage of water in properly soaked newsprint is approximately the same as in live tissue (muscle).

The length of the cellulose fibers that are aligned in one direction (like muscle fibers), in newsprint is about the same as the fibers in muscle tissue.

Crosswise, the cohesion of newsprint is about the same as muscle fibers.

So at a quasi microscopic level, the characteristics of the both media are much closer than they would seem to the casual observer.

Not trying to convince Ron, just trying to put forth some more information for the rest of the readers. I am sure some will have the initiative, energy and courage to do their OWN testing, and not rely on anecdotal evidence.

As for experience, this is the result of 2 hours night WORK (got paid for it) in a four stories, air conditioned, inside plumbed,  elevators equipped, STABLES for race horses:

 

Keep well and shoot straight!

 

 

 

HM


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Hector J Medina G
(@hector-j-medina-g)
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Joined: 1 year ago
Posts: 243
2019-01-06 09:14:13  

@ Jacob;

Yes, it was clear that the video wasn't yours.

The problem with real life is that is never so simple as it seems. When hunting you need to think that shot placement is first and foremost and that life will not always give you a clear head shot at a reasonable range to  be a purist. When needing to get rid of pests, you need to take a broader perspective (but still be ethical and legal) about the shot you are taking.

In ALL living critters, you need to think that you have a "jelly" core that is surrounded by muscle and bone. It is this "Jelly Core" what need to obliterate for a quick, humane, death.

In flying critters, also remember that the ONLY bones that need to be strong are those that are structurally important, and those are the wing/shoulder bones. All others are designed for lightness.

In four legged critters, the constitution of some bones belie their location. For example, the forehead of O'Possa or badgers, or the forelegs of moles and Prairie Dogs are very strong. It's all about function.

Best shot placement, again, needs some knowledge of the specific anatomy of the animal you are hunting.

With all due respect to your military friend, his real life experience is (I would hope) limited to Ball/FMJ rounds. Only police/SF's can use HP's and even then, not all PD's accept their use.

SOME ball ammo is designed to tumble upon impact, but this is a completely different story.

The 9 mm's vs, 0.45 ACP situation has so many more details that need to be put into context that it is really not relevant to the discussion about pellets and airguns.

In GENERAL airgun terms, the size of the wound channel has nothing to do with the speed of the projectile, the permanent wound cavity comes from the Terminal Diameter of the pellet in question and the head shape. A dome will leave a smaller wound channel than a WC; a HP, depending on the design of the head can behave like a WC or create secondary wound channels if it fractures upon impact.
The advantage of the HP is that, in some cases, it flies almost as good as a good dome, but upon impact, it  increases its frontal area/diameter and acts inside the "jelly" core as a much larger caliber round.

And in these last two phrases is the clue:

Good HP projectiles are designed to USE the layer of muscle as an opening-up resistance stage. 
I've measured 0.177" Crow Magnums  that ended up almost 0.22" cal.

The BHE of the article ended up between 0.20" cal and 0.22" cal. Again, it is this frontal area what defines the permanent wound cavity. It is NOT a question of shock wave, it is a question of tissue destruction. Some of it will be destroyed by direct contact with the projectile, some other will be destroyed by the rest of the tissue pulling it by acceleration due to the impact speed.

Anyway, there is no substitute for first hand experience, so take your pick of ballistic media, whatever it is, and compare YOUR pellets from YOUR rifle at YOUR distances.

Be methodical and keep notes. You will reach your own conclusions and that is what counts for YOU.

Keep well and shoot straight!

 

 

 

 

 

 

HM


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pistolero
(@pistolero)
Joined: 1 year ago
Posts: 307
2019-01-06 17:33:58  

Jacob, Hector and others,

I could tell the video wasn't your doing Jacob, and you presented it for interest's sake; so I wasn't directing any of my comments at you. Matter of fact, besides the weird test medium, I couldn't figure out why some of the shots supposedly through the foil tube didn't seem to pass through it. In fact one shot seems to show three projectiles at once impacting around the foil tube. That made me lose all confidence in the video.

Sorry I can't give you credit for my mirth Hector. Truth is I only scanned through your first post in passing, and didn't view the link that I assume by your understandable reaction references wet newspapers (true confessions, I still haven't... but promise to later). The sources of my test-mediums-mirth (alluded to in my previous post) actually predate our acquaintance by about a decade, Bud. Sorry 'bout that. I won't mention names attached to the toes I managed to step on 20 years ago by mocking their airgun terminal-ballistics testing in The Manic Compressive, but suffice to say they were well-known airgun personalities for years prior to 1998, and most everyone reading this would recognize them. Had I viewed your link Hector, I'd have omitted wet newspapers as hilariously dissimilar material to tissue, and just mentioned two-by-fours (and aluminum foil, of course).

More true confessions... while I'm spillin' my guts. I did find Jacob's post and attached video interesting. And I've found many of Hector's posts and live conversations intensely interesting, always well-reasoned, and based on vast experience and scientific testing/analysis... even some of the more 'thorough' theses I can't quite follow! (Or am simply too lazy to try.)

It's all good, Gentlemen. Happy shooting, All! 

"No brag; just fact."- Will Sonnett


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 1 year ago
Posts: 243
2019-01-08 10:40:44  

Ron;

It's all good, no worries mate.

We've discussed "spiritedly and energetically" other airgunning aspects before, and I know you are completely sincere, genuine, and convinced of your experiences. We may have different ways of interpreting results, but I do respect immensely your experience.

Hope Texas is having better shooting weather than the northeast. 

Keep well and shoot straight!

 

 

 

 

HM

 


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