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PostPosted: Fri Sep 13, 2013 2:33 pm 
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Nonsense. Sorry, but my 440fps Baikal 46m shooting an RWS hollowpoint pellet into Duct Seal shows an expansion of about 20% diameter. Duct Seal is soft, and 440fps is slow. The same pistol also makes wadcutters expand, but only slightly. Points not at all, just crumpled at the waist slightly. Predator Polymags? Most shots into Duct Seal peel the hollowpoint leading edge back about 1mm and spread the diameter about the same, to 5.5mm, and they spread even more shot into an unripe walnut. Hollowpoint or compound hunting point pellets spread more easily owing to the much reduced structural strength at the smaller scale compared to firearm projectiles. It's the same lead, only much thinner walls, so it's weaker.


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PostPosted: Fri Sep 13, 2013 5:34 pm 
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The statement "Duct Seal is soft" is very subjective.... Penetration is very limited, not unlike what you get with paraffin wax (OK, a bit more).... Compare the penetration in Duct Seal to what I got in melt-and-pour soap, which you would probably not consider "soft"....

topic53095.html

How the expansion of a hollowpoint pellet relates to what it does in flesh bears little resemblance to how "hard" or "soft" the substance feels to the touch... Duct seal yields to low pressures applied slowly but reacts as a hard substance to a sudden impact.... Soap feels hard, but is much more easily penetrated by a pellet.... Arguments can be made for and against how each represents the impact of a pellet on flesh, but the melt-and-pour soap I used seemed much more realistic in both the penetration and expansion than what I have seen with wood, phonebooks, paraffin wax or duct seal (all too hard), vs. water, plumbers putty, playdoh, and ballistics gel (IMO all too soft and/or temperature sensitive)....

Of particular importance is the non-PAL testing at the bottom of page 3 of that thread.... NO expansion of any of the pellets at ~400 fps.... The penetration was about 3/4" in .177 and about 1" in .22 cal.... How far do pellets penetrate into Duct Seal at that velocity?....

Bob

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PostPosted: Fri Sep 13, 2013 5:50 pm 
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Well I'll consider myself schooled, I guess. Not about to invest in any 'melt-and-pour' soap, whatever that is supposed to be used for. Specially shaped gift soaps or some such? I've no use for that unless I become obsessed with pellet penetration and deformation characteristics... which seems somewhat unlikely. Seems rsterne is holding up that end just fine, so I'll bow back out of this conversation. :oops:

But your mention of water intrigued me. Hadn't thought of that. So I filled a gallon plastic pail and put a 1mm thick cardboard layer on top, let it soak about 10 seconds then shot with a Predator. Nice little dent in the bottom not quite through the plastic, with slight deformation of the pellet head but no increase in diameter. Surprising that a 440fps pellet can get through 10" of water. Even more surprising that some would consider water a suitable testing medium for hollowpoint deformation, as it's obviously too 'soft.' But mostly I was curious to see if it'd stop the pellet, which it didn't at all. Saw an ultra-slow video of an AK-47 shooting underwater a month or so ago, and no bullet travelled beyond 6 feet or so. I'll have to try with deeper water and see what happens sometime.

rsterne wrote:
Of particular importance is the non-PAL testing at the bottom of page 3 of that thread.... NO expansion of any of the pellets at ~400 fps.... The penetration was about 3/4" in .177 and about 1" in .22 cal.... How far do pellets penetrate into Duct Seal at that velocity?....


Oops, forgot this bit. I said 440fps for the Baikal, not 400fps, but still... Predators in .177" 13mm into well used Duct Seal (cleaned maybe 20 times, a fair bit of embedded paper toughening it slightly) to the plastic tip, 11mm to the front edge of the lead. Here's a snapshot of what a .177" Predator Polymag looks like after going 11mm (or 13mm if you counted the point) into old Duct Seal:
Attachment:
predator_into_ductseal.jpg
predator_into_ductseal.jpg [ 30.42 KiB | Viewed 553 times ]


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PostPosted: Fri Sep 13, 2013 6:06 pm 
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I was just curious so I just pulled out some (new) duct seal and tested two .177 pellets at ~500 fps.... JSB Express imbedded with the skirt about 1mm below flush and shortened significantly and flattened and expanded a bit.... RWS SuperHollowPoint stopped with the skirt flush, the hollowpoint opened up nearly completely, and the pellet (which starts out longer than the JSB) about the same overall length.... I didn't use calipers, just my eyeballs, and the penetration (even though the velocity was higher than my soap tests) was about 1/3rd as much.... and the pellets did indeed expand significantly (which didn't occur in the soap).... This occurs despite the fact that you can push your finger into the Duct Seal but you can't do that with the soap....

About all these tests both show is how pellets react at differenct velocities in different substances.... and that how hard or soft something feels is not necessarily related to the penetration or expansion.... I wish I could remember where I saw the video demonstrating this.... It had a guy standing on a puddle of "something" and he slowly sank into it.... However, when hit with a hammer (or stomping on it hard) there was virtually no penetration.... The sudden impact "hardened" the substance, just like happens with Duct Seal.... I "think" it was a mixture of flour and water, but I'm not sure....

Bob

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PostPosted: Fri Sep 13, 2013 6:28 pm 
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I found it.... "Non-Newtonian Fluids".... one example being cornstarch and water....

http://www.youtube.com/watch?v=JGfynrsdaV0

I suspect (but have no proof) that Duct Seal acts in this way....

Bob

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Airsonal;
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Proud Member of the 2000+fps Club!


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PostPosted: Fri Sep 13, 2013 6:46 pm 
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Probably starch of some sort. Usually it's corn starch as it's the cheapest for large scale wasteful fun like that. My kid uses corn starch for 'science' stuff at school and friend's houses all the time. Mix a batch 50/50 with water in a large bowl, take it outside, and whack away until it's all over everybody. It's called a 'non-Newtonian fluid' if you're interested in hunting down Youtube videos, of which there are PLENTY!

Duct seal may or may not behave in a way similar to starchy water, not sure how one would find out. I know that modelling clay will take a pellet much, much deeper than duct seal, which is why I stopped using the clay for pellet traps. Too hard to clean.

Okay, I guess I ought not to pull the bowing out routine... I'll keep a hand in and stay civil of course. My thoughts on pellets such as Predators and hollowpoints of various varieties run in a way slightly different from the pourable soap stuff might demonstrate. Not that the soap isn't lovely for demonstrating penetration and expansion. But that soap's relevance for hunting purposes (really the only legitimate reason for these sorts of pellets, especially the more expensive polymer-tipped variety) isn't very clear. It might be, if the soap happens to have a similar effect on pellets as does a gut shot for instance. But no conscientious hunter would ever take a gut shot, right?

So, if one were to take a heart/lung shot on a small animal with a 400-500fps airgun - let's use your number of 400fps at point of impact for argument's sake - then there's a better than 50% chance of that projectile striking a rib, correct? Where's the rib in your soap?

And if one is pesting, squirrels or rats for instance, and taking the arguably 'kinder' head shot just below the ear from the side, then there is a 100% chance of striking thin fur and skin, then bone from between 1mm and 3mm thickness before striking the brain. That bony layer is going to cause considerably different pellet deformation of a hollow or polymer pointed pellet than what happens in your soap castings. If you were to add a layer of bone, or for convenience a layer of 2mm hard plastic such as acrylic sheet to emulate bone, then the resulting pellet deformation might bear more relevance for such a pellet's use in the real world, outside your secret laboratory. I'd venture a little further and suggest that in such a demonstration your soap might be too hard to provide an accurate analogue to brain matter.

Hm. I wonder what I have around the shop... Oh, my kid's got some 'slime' he made the other day, that's about like a brain. I know brain texture only too well. My father was Croatian. Breakfast still gives me the shivers sometimes, and it's been over 40 years since choking the stuff down with under-cooked eggs... say no more. Anyway, this slime is virtually identical to raw brain tissue in texture and resistance to slow and/or fast impacts. It's made of water, transparent 'craft' glue from a dollar store, and about 1/3rd teaspoon of borax powder. Really neat stuff for a kid to make by the way, kind of a miracle and really cheap compared to the usual commercial slime balls. Some green food colouring and my boy is all about that. So I took his slime and put it on top of 8 layers of stiff card in a plastic cup to prevent bottom penetration, put a layer of 2mm plexiglas on top of that for the 'bone', then a layer of 0.5mm cardboard for the skin and wee bit of fur just under the ear. Seemed about right. Then I fired a Predator point blank. I expect at a usual pesting range of 20 feet or more the deformation from an airgun with a muzzle velocity of 440fps would be about 400fps, so the deformation would be somewhat less but similar. Here's the result. The pellet bounced off the top layer of bottom card, leaving only a trace of a dent but coming right back up to the shattered plastic layer. Kind of like a description I read once of how Mafia hitmen like to use small .22" pistols up close, as the bullet tends to rattle around inside the head causing much more damage than a through-and-through shot. And as a further bonus; I just spent 3 minutes plucking tiny bits of shattered plastic 'skull' out of my kid's slime so he won't be mad at me. Had to ask for the use of the slime, and he said "Sure, as long as you take any little bits out of it after, and put back ALL the slime, don't waste any!" He's 7. Aren't 7 year olds cute? Anyway, here's the pellet beside the intact Pred and the one into duct seal:

Attachment:
predator_through_card-plastic-slime.jpg
predator_through_card-plastic-slime.jpg [ 28.62 KiB | Viewed 547 times ]


Ah, took too long concocting this experiment and you beat me to the non-Newtonian thing. Fun stuff, eh?


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PostPosted: Fri Sep 13, 2013 9:40 pm 
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I'll have to admit, your test is creative, and every bit as accurate as using soap.... That's assuming that 2mm plexiglass is a good substitute for bone and slime is a good substitute for brain tissue.... It's a bit hard to see the wound channel or photograph it, though....

I assume the idea of testing a bunch of different pellets at a consistent energy level in a consistent medium wasn't lost on you.... and I'll further assume you read my thread through to realize I didn't claim if to be a perfect rendition (in fact it wasn't intended to be) of testing through skin and bone, but that I felt it to be a reasonable approximation for tissue.... certainly a lot more realistic than Duct Seal (or phonebooks or wax or wood or water)....

Pellets expand (or at least flatten) when they hit a hard surface (like bone, wood or plexiglas) and they don't expand as readily in water.... Everything in between will have a "magic velocity" for any given pellet where we can claim (show) it expands or not.... If you increase the velocity, the pellets will expand more, and eventually they will likely come apart, particularly if there is any cavity in the nose....

If you want to see the ultimate in expansion, shoot a pellet at 90* to a steel plate.... Even a relatively hard pointed pellet that won't expand at all in an animal at non-PAL velocity will show significant expansion.... and that proves.... nothing....

Bob

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Airsonal;
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Proud Member of the 2000+fps Club!


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PostPosted: Sat Sep 14, 2013 12:07 pm 
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Playlist of gummy bear shooting.
Non-newtonian bear targets.

Some things is sucks up are pretty impressive.
http://www.youtube.com/watch?v=ggH_oMCA0mQ&feature=c4-overview-vl&list=PLg3un-iGWxl3uehdls9C9LrLZc6_PuLTg


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PostPosted: Sat Sep 14, 2013 12:12 pm 
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rsterne wrote:
I'll have to admit, your test is creative, and every bit as accurate as using soap.... That's assuming that 2mm plexiglass is a good substitute for bone and slime is a good substitute for brain tissue.... It's a bit hard to see the wound channel or photograph it, though....

Which wasn't my point. While the topic itself is regarding speed for a hollow point to expand, the OP did state rather clearly that he'd tuned his rifle and was "Super excited to go hunting with it." This would seem to make a simulated small game skull somewhat more relevant than your elegantly consistent and visually splendid experiment with pourable soap. Such soap is wonderful for testing relative expansion/penetration of various pellets at various velocities, but bears a closer physical analogue to organs than it is to skin and bone and organs together.

One can't easily photograph the wound channel in a squirrel's head... unless one has access to an X-ray machine, or perhaps freezes said squirrel then carefully saws the head into sections parallel to the shot path. I readily acknowledge that having done no brittleness/penetration testing on actual small animal skulls my approximation using 2mm plexi is no more than a guess. Something about 1mm thick and slightly more flexible might be a better choice for testing. I think the slime is a good approximation to brain texture and resistance. If anything actual living brain might be slightly tougher, but I doubt that the brain itself would cause any pellet to expand at all as brain tissue is mostly water. The card stock seemed about right to simulate skin with little fur, being somewhat resistant to puncture with a 5mm awl having a moderately sharp point but not very. All in all one could try harder to find exact analogues to these tissues... but for me that'd be trying too hard. Close enough, I think, to the actual thing OP is asking about.

rsterne wrote:
I assume the idea of testing a bunch of different pellets at a consistent energy level in a consistent medium wasn't lost on you.... and I'll further assume you read my thread through to realize I didn't claim if to be a perfect rendition (in fact it wasn't intended to be) of testing through skin and bone, but that I felt it to be a reasonable approximation for tissue.... certainly a lot more realistic than Duct Seal (or phonebooks or wax or wood or water)....


Guilty. I read every word in that thread, and was impressed by your persistence and thoroughness, within the limits of the experiment. Again, my apologies for bringing in my smarty-pants initial reference to a sort of hollow point (Predators are hollow point pellets, just assisted by a hard plastic point in achieving initial penetration and in maintaining higher velocity - in my Chrony tests the 8gr Preds run at exactly the same velocity as 7gr wadcutters through the same pistol, where true hollow points at 8gr are about 10fps slower) going into the terribly irrelevant duct seal. I'm not persisting in claiming any duct seal relevance, nor have I mentioned phonebooks, wax, wood, nor water.

rsterne wrote:
If you want to see the ultimate in expansion, shoot a pellet at 90* to a steel plate.... Even a relatively hard pointed pellet that won't expand at all in an animal at non-PAL velocity will show significant expansion.... and that proves.... nothing....


My home 10m range has something almost like that; a 3mm steel plate angled at 45 degrees with a bed of duct seal to damp ricochets. There's also about a pound of duct seal smeared onto the back of the plate, then some foam and cardboard and duct tape. The result is an almost-silent impact, but the pellets get pretty much smashed into flat things hard to recognise as pellets. Not relevant to hunting at all, nor have I claimed it was relevant, nor even mentioned steel impacts. Is anyone talking about hollow points on steel here? Or phone books of all things?


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PostPosted: Sat Sep 14, 2013 12:25 pm 
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Timooner wrote:
Hi! I was wondering what velocity is neccesary to cause hollow point pellets to explode or expand on impact. The reason im asking is I recently tuned my .22 pellet gun, with which before the pellets never expanded in wood, now with the tune they seem to explode and disintegrat within the wood. (I cut the board in half and examined the pellet fragments) So, what fps would my pellet gun have to be firing at atleast to cause such carnage. Super excited to go hunting with it.

Thanks, Ryan.

I have used so many gimmicky pellets in 40 years of hunting or pesting what ever you want to call it I never found the killing power of them any better than just a basic domed pellet i would put more concern on shot placement ....


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PostPosted: Sat Sep 14, 2013 12:39 pm 
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lauchlin wrote:
Timooner wrote:
Hi! I was wondering what velocity is neccesary to cause hollow point pellets to explode or expand on impact. The reason im asking is I recently tuned my .22 pellet gun, with which before the pellets never expanded in wood, now with the tune they seem to explode and disintegrat within the wood. (I cut the board in half and examined the pellet fragments) So, what fps would my pellet gun have to be firing at atleast to cause such carnage. Super excited to go hunting with it.

Thanks, Ryan.

I have used so many gimmicky pellets in 40 years of hunting or pesting what ever you want to call it I never found the killing power of them any better than just a basic domed pellet i would put more concern on shot placement ....

Couldnt agree with you more upon that statement. I have found that upon the JSB Preds velocities at over 900fps do create a significantly larger woound chanel upon the unfortuate ones that are hit with them.

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PostPosted: Sat Sep 14, 2013 3:24 pm 
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Rather than continue the rather pointless argument about testing pellets on anything other than an animal, I will again offer my opinion that in a non-PAL airgun, hollowpoints will offer little if any expansion on a living creature.... I reserve the right to reverse that (heck I'll even apologize!) when and if some proof appears to the contrary in the form of a photo of a hollow point pellet shot from a non-PAL airgun and recovered from an animal that shows such expansion.... A description of what animal was hit and where would be useful information, of course....

Bob

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Airsonal;
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Proud Member of the 2000+fps Club!


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PostPosted: Sat Sep 14, 2013 4:27 pm 
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rsterne wrote:
Rather than continue the rather pointless argument about testing pellets on anything other than an animal, I will again offer my opinion that in a non-PAL airgun, hollowpoints will offer little if any expansion on a living creature.... I reserve the right to reverse that (heck I'll even apologize!) when and if some proof appears to the contrary in the form of a photo of a hollow point pellet shot from a non-PAL airgun and recovered from an animal that shows such expansion.... A description of what animal was hit and where would be useful information, of course....

Bob


I think that would be a good one for Gordo! He likes disecting and looking for wound channels!

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PostPosted: Sat Sep 14, 2013 5:25 pm 
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Ew. Just ew. Gordo eats bears. Double-ew.


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PostPosted: Sun Sep 15, 2013 10:38 am 
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I used predators from my HW97 .177 on the ground squirrels I shot in July. That rifle drives them at 890fps and from the exit holes and blood loss on a few I didn't post pictures of, I'd suspect they all expanded somewhat - on the skulls or neck bones (low hits). They worked VERY well indeed.

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