GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: mpbby on September 03, 2018, 03:53:14 PM
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Please consider: - a magnum springer 0.22 with about "20-30" fpe close to the muzzle; 'domed' pellets; shot distance about "20" yards.
In practice.., when choosing pellets, once no issues about accuracy, if, by far, the MAIN practical objective is - penetration (head shots for hogs), what should be the best correlation to GUESS* the sweet spot - fpe or momentum?
* As we don't have the ideal conditions to the actual 'penetration test' (including different hog craniums.., ages/sizes, bone thickness/hardness), it seems to me we would have to - guess, based on the chrony numbers, maybe ChairGun, approximated BC and labeled pellet's weight.
Thank you,
Marcos
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Manny has given us some pretty good data on this, check him out in the hunting gate (Nomadic Pirate)
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Penetration for non-expanding projectiles of similar shape is proportional to the Sectional Density times the Velocity.... Therefore, for a given caliber, it is proportional to the Momentum.... Chairgun has a "Penetration" calculator that works exactly that way.... but there is no allowance for expansion or shape.... It will predict the same penetration for a wadcutter, or a round-nose, or a pointed or a roundball….
Bob
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Thank you, Bryan, but Manny didn't go as deep as I wished with the humble springer .. He wants 'results', and the powerful PCPs bring them much easier; simply no worries about penetration.
Thank you, Bob, I'm still a kind of blind/dumb in this subject. I use ChairGun just for some VERY basics, most of the time with 'graph and table'; when I mentioned it was only regarding the speed at the target ("20" yards), when you don't measure 'there' with the chrony. Thank you for pointing me. I never noticed .. there were the columns for .. momentum - and - penetration!?
I don't know if the different pellets will tend to perform "proportionally" through bones, but, at least, there is this objective referential to consider. Regarding the shape, you did share that excelent job..
All together, I'm feeling able to the 'best guess'..
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I'm still waiting for my friend to shoot a pig...that way I can ask for the head, since he doesn't keep them. I'll skip point-blank testing; I'll set up the head at 20 yards and test penetration with different ammo.
On a slightly different note, what would be a comparable medium for bone? I know flesh is ballistics gel, but what would be similar density/hardness materials that would accurately replicate bone so that we can test for penetration?
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You can probably just get some bone for that. Call around, check with local butchers and etc.
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I use melt-and-pour soap.... It is firmer than ballistics gel, but not as firm as paraffin wax.... I find it a good compromise, it is consistent, and reusable.... A .22LR HV bullet penetrates about 11", and a HP half that....
Bob
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Of course, shot placement is most critical.
Recently I’ve seen an x-rays of an animal’s head with several pellets that did not penetrate....
One reason for this is the angle at which the pellet connects with the bone. If it hits perpendicular, fine. But the shallower the angle, the easier the pellet can be deflected and go through the surrounding flesh but not through the bone.
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Of course, shot placement is most critical.
Recently I’ve seen an x-rays of an animal’s head with several pellets that did not penetrate....
One reason for this is the angle at which the pellet connects with the bone. If it hits perpendicular, fine. But the shallower the angle, the easier the pellet can be deflected and go through the surrounding flesh but not through the bone.
I wonder if there would be a noticeable difference in glancing penetration with different head shapes. Like if the corners of a wad cutter would be preferable.
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You just don't attempt a headshots from a glancing angle, especially with airgun power. it is as simple as that. That is a part of hunting, you have to wait for the right shot.
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^X2000....
Bob
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don't really have any butcher shops here to ask for skulls/heads.
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Maybe it's already time to the actual experience. Right pellet shape, top group for 'momentum', good grouping up to "22" yards, (if available) good news from the trail cam, confortably rested, patience for shot placement/angle.. what's going to happen? ::)
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I predict a piggy for my friend Marcos! 8)
If I may offer a suggestion: before the actual day, put up some targets at 10, 12, 15, 18 and 20 yards. See how your point of impact is at all those ranges and make a mental note of how much lower or higher you have to aim.
And then where you'll be shooting, put some sticks into the ground at the same yardage. That way your ranges will already be set and all you need to do is remember how low or high to shoot.
Good luck and shoot well!!!
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I was thinking about Guam, not here.. :(
If you trust ChairGun, depending on the pellet of choice and your 'zero' distance for the scope, you may have a continuous PBR ("point blank range"), for instance, within +- 0.3" from 10 to 20+ yards; no needs for compensations when aiming.
If it was my case, and after all the planning, I would keep my mind managing the adrenaline ("buck fever" as I have learned from you, American hunters, how to call in English my very usual symptoms..). ;D
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Oh. Lol ;D Hopefully soon, Marcos. We just had a typhoon blow through here, so I haven't been jungle walking. Things are starting to get a little more settled, so maybe in the next couple of weeks I can get out there and see what's moving around.
Chairgun I haven't tried using yet. I don't know if it means anything, when the scope was on the Magnum, I had different points of impacts at different yardages. 10 yards required aiming low and to the right, 15 yards still required aiming a hair low and still to the right, just not as much. 20 yards was spot on with the 14.3 CPUMs, a little high with the 16.7 Red Flights and just slightly higher with the 17.9 Sniper Magnums.
30 yards out? Had to aim a little LOW with the Sniper Magnums. Uhm, excuse me, what? Yes... low. It was just the standard Gamo scope, but still...low? That means pellet is still rising, yes? I need to shoot further out than 30 yards to test projectile path.
I think I'm going to set iron sights at 15 yards and then set scope (I have a peep rail) for maybe 25-30.
Don't know what's going on, but if Maggy is zeroed in at a particular range under 30, she's nickel holes all day without too much effort. Maybe I need another scope? Or maybe a better right eye? :o
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I will send you a PM.
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At the risk of reviving a dead horse, I had anther thought on the topic:
When you fire a 8 lb .308 Winchester hunting rifle, the gun and the bullet have about the same momentum (Actually, the rifle has a little more because of the mass and velocity of the ejected propellant gasses). However, the bullet carries about 2500 ft.lb at the muzzle; while the rifle carries only about 12 ft.lb.
If momentum predicted penetration, then no one would volunteer to shoot a hunting rifle more than once. Thus, it is clearly the ratio in FPE between the projectile and the gun that makes shooting something useful. As in, punching a hole in the target, rather than puncturing or dislocating your shoulder.
Now, you may be asking if a lighter faster projectile would penetrate clay or ballistics gel further, than another pellet of a similar caliber, when the second projectile is heavier, but travels proportionately slower? In that case, the heavier projectile may very well penetrate deeper because it is going slower. This is because drag against a body travelling at high speed through a fluid is exponential with velocity; rather than because momentum is more useful than energy.
You might care to test this out; using different projectile weights of the same caliber and form; shot at velocities that normalize first, energy; then momentum. For sticky viscous materials, such as soap, clay, ballistics gel and flesh; reducing the velocity by adding mass should increase penetration. That is, unless the projectile was already moving so slowly that the lack of energy was limiting penetration...
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While the rifle may have the same Momentum as the bullet, the area of the butt pad is significantly larger than the caliber.... and hence no penetration occurs, only a rearward displacement of the rifle and the shoulder supporting it.... If you fired the rifle without it leaning against your shoulder (which effectively adds additional mass), you may be surprised at the velocity it achieves, even though it has about 400 times of the mass.... Perhaps hanging the rifle from a rope as a Ballistics Pendulum would be educational?.... It would certainly be entertaining.... 8)
You are absolutely correct that generally heavy projectiles have greater penetration for the same FPE.... They also have greater Momentum, since the velocity is squared in the energy calculation, but not in the momentum one.... If you double the projectile weight, for the same energy the heavier projectile has 1.414 times the momentum, and you can expect (roughly) 1.4 times the penetration.... without any expansion or tumbling, and for similar shapes, of course....
A good experiment would be to cast identical projectiles of lead (SG 11.3) and tin (SG 7.3)…. Launched at the same FPE, the tin bullet would have 24% greater velocity, but only 81% of the momentum of the lead bullet.... If they were shot into a uniform medium such as ballistics gel, at airgun velocities, and no expansion or tumbling occurred, I would expect that the lead bullet to have 24% greater penetration....
Anecdotally, I did a test of the 14.3 gr. JSB Exact Express and the 18.1 gr. Exact Heavy in the same rifle, fired into melt-and-pour soap at 20 FPE.... The 14.3 gr. penetrated 87 mm and the 18.1 gr. penetrated 98 mm.... The predicted penetration difference is SQRT(18.1/14.3) = 1.125:1.... Note that 87 x 1.125 = 98.... Pretty good correlation with theory, no?....
Bob
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AirArmsHuntingSA posted a video on youtube with 6 different guns and pellets that had interesting results. I can't post links for some reason, but the url ended in watch?v=xXhg9J44mWk
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At the risk of reviving a dead horse, I had anther thought on the topic:
When you fire a 8 lb .308 Winchester hunting rifle, the gun and the bullet have about the same momentum (Actually, the rifle has a little more because of the mass and velocity of the ejected propellant gasses). However, the bullet carries about 2500 ft.lb at the muzzle; while the rifle carries only about 12 ft.lb.
If momentum predicted penetration, then no one would volunteer to shoot a hunting rifle more than once. Thus, it is clearly the ratio in FPE between the projectile and the gun that makes shooting something useful. As in, punching a hole in the target, rather than puncturing or dislocating your shoulder.
Now, you may be asking if a lighter faster projectile would penetrate clay or ballistics gel further, than another pellet of a similar caliber, when the second projectile is heavier, but travels proportionately slower? In that case, the heavier projectile may very well penetrate deeper because it is going slower. This is because drag against a body travelling at high speed through a fluid is exponential with velocity; rather than because momentum is more useful than energy.
You might care to test this out; using different projectile weights of the same caliber and form; shot at velocities that normalize first, energy; then momentum. For sticky viscous materials, such as soap, clay, ballistics gel and flesh; reducing the velocity by adding mass should increase penetration. That is, unless the projectile was already moving so slowly that the lack of energy was limiting penetration...
How does a 170 grain 30-30 Winchester load outpenetrate so many different (and far more powerful, faster, heavier, or lighter) 30 cal rounds? I think it's magic. Or maybe has something to do with optimal velocity, hardness, and cross sectional density for a given .30 cal hunting rifle pushing a 170 grain projectile, chosen specifically for a hunting rifle at a given power level pushing a soft point bullet. Vs. A 30/06 Springfield, designed to push a heavier full metal jacket round for military service, or 7.62 Nato developed for use in gas operated autoloading service rifles- again, pushing FMJ's.
I literally hate this argument. I made the mistake of clicking it, Lord help me!
The same reason the mass of the rifle protects you, is the same way that the mass of a projectile drives through tissue. And that has a lot to do with momentum.
Another example. The heavier 10-ish grain version of a pellet will outpenetrate the 8-ish grain of the same brand/type every single time, when fired from the same rifle, even at the expense of nearly 10% of muzzle energy due to the mechanics of a spring gun becoming less efficient behind the heavier pellet. The momentum and yes, cross sectional density, are what make up for that. Except, there is little to no expansion to speak of in gel with a good dome pellet... so the cross sectional density plays less of a role, than the mass/momentum of the projectile.
What about the drag caused by the longer pellet, and longer skirt?
There is no single variable that you could possibly single out as the key variable to penetration. Velocity, to a point, untill you reach the threshhold for a projectile to hold together, right? Because if the rifle stock were moving the same speed as the projectile, it'd probably tear your shoulder clear off and explode into splinters.
I lived through three tornadoes as a child. One thing I learned from them, is that with enough velocity, a lot of soft things can zip right through a lot of hard things. Everything has a limit, just like a bullet moving fast enough can turm to dust on a target. Still might poke a hole in it. And still, a heavier pellet out penetrates a light one of the same type and composition at the same or approx. 10 percent less energy every time.
A lot of people measure penetration in thingd like wood by sticking something in the hole. That is a mistake. The nose of the pellet marks the penetration, it is often deeper even though the hole is shallower because the pellet is longer.
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The primary reason why heavier projectiles of the same caliber penetrate flesh, soap or gel better is the same reason they penetrate air better: A higher BC.
Heavier pellets may favor the "momentum rules" theory, but the other reason for their velocity retention (in air and flesh) is that they generally start out at lower velocity. If you take a range of pellet weights and shoot them at increasing velocities, their penetration in soft ballistics media is strangely non-linear with with regards to both energy or momentum.
What happens is that the faster a pellet is driven, despite being heavier, the more of its forward energy and momentum are transmitted as "radial wounding":
The video below looks at the behavior of a range of .22 caliber airgun pellet weights, driven at increasing velocity; when fired into clay. The video ends with a .22-250 shooting the same clay block with a 50 grain bullet at 3600 FPS. The latter carries a huge momentum advantage, yet falls far short of penetrating "proportionately deeper" than the the 12 ft.lb airgun pellet.
https://www.youtube.com/watch?v=xXhg9J44mWk&feature=youtu.be&t=190 (https://www.youtube.com/watch?v=xXhg9J44mWk&feature=youtu.be&t=193)
The reason a 170 grain .30-30 penetrates so well also involved better BC. It is also explained by the same reason a 150 grain .308 Win soft point penetrates through a deer broadside at 300 yards, while it may end up just under the skin on the far side when shot from less than 50 yards. This, despite the longer range bullet carrying less velocity, energy and momentum: Greater velocity drives greater bullet expansion. A wider bullet increases the volume of the wound, but decreases maximum penetration depth.
Conversely, heavy slow bullets carry more energy at longer ranges, and expand less due to their lower velocities. Thus heavier bullets have higher BC in air before impact, and higher "BC" in flesh after impact.
In the context of a feral hog rather than a rat's skull; when it comes to bone, there is a definite threshold velocity. Below this threshold velocity penetration becomes unlikely, and deflection much more common. So, providing you have sufficient velocity, a heavier pellet of a given caliber will penetrate bone better.
Thus; penetration of robust bones is like shooing at the side of a soup can: A .25 pellet at 300 FPS just makes a large dent in the can, and knocks it away in spectacular fashion; while a .177 pellet at 600 FPS punches right through both sides, hardly moving the can. In this case, the higher momentum pellet just pushes the can further away.
Even with the same caliber; if you double the pellet weight and halve the velocity, such that momentum stays the same; a 600 FPS pellet is going to penetrate bone better than a heavy one at 300 FPS. On the other hand, if you compare a light pure lead pellet at 1350 FPS to one 50% heavier at 900 FPS (same momentum), the slower heavier pellet will probably penetrate both bone and flesh more consistently due to its lower propensity to expand or fragment.
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But, the .22-250 was pushed too fast for the bullet to hold together. Any soft point or even thin jacketed bullet pushed that fast into clay will come apart.
Edit- FYI- ballistics coefficients for 30-30 bullets not so good
And another edit- at most airgun velocities, fragmentation is not much of a factor.
Now, lets see what happens with those tests, shooting copper solids from every weapon.
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But, the .22-250 was pushed too fast for the bullet to hold together. Any soft point or even thin jacketed bullet pushed that fast into clay will come apart.
FYI- ballistics coefficients for 30-30 bullets not so good
As always; the devil is in the details.
Round nose heavy .30-30 has poor form, but gets away with it due to its low velocity....
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Now, lets see what happens with those tests, shooting copper solids from every weapon.
Copper spitzer bullets will tumble in gel or flesh. This will reduce penetration and make it somewhat unpredictable.
Copper diabolo pellets will remain point forwards because they will be drag stabilized. They should penetrate better than lead pellets when driven over 1000 FPS, but will still not penetrate clay proportional to their momentum. See the non-expanding round pellet nose performance in Dubber's video. Copper pellets will behave similarly; just up to higher velocities.
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Fmj's will tumble as well. Still penetrate very good.
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And another edit- at most airgun velocities, fragmentation is not much of a factor.
Nielsen Specialty Ammo may beg to differ :) Look at the expansion of the NSA slugs in the video. If these hit a larger animal or heavy bone, they will fragment...
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Fyi i'm not referencing nor have i even watched dubber's video. This is not ground breaking stuff. And im not advocating one variable over the other, instead I am saying that energy itself is obviously not the key
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And another edit- at most airgun velocities, fragmentation is not much of a factor.
Nielsen Specialty Ammo may beg to differ :) Look at the expansion of the NSA slugs in the video. If these hit a larger animal or heavy bone, they will fragment...
There are exceptions to everything. Just like the 30-30. Pretty much no good on paper, compared to every other .30 cal cartridge. Inside 100 yards, will out penetrate them all, and still get good expansion.
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Found some interesting data here: http://www.brassfetcher.com/Airguns/177%20Caliber%20Airgun.html (http://www.brassfetcher.com/Airguns/177%20Caliber%20Airgun.html) not sure how they got all the intermediate velocity data. It will take a bit of time to work through all of it.
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Thank you, Stan. That test data is brilliant!
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Found some interesting data here: http://www.brassfetcher.com/Airguns/177%20Caliber%20Airgun.html (http://www.brassfetcher.com/Airguns/177%20Caliber%20Airgun.html) not sure how they got all the intermediate velocity data. It will take a bit of time to work through all of it.
Very cool, thanks for sharing. I would assume the intermediate velocity data comes from extending the range.
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The brassfetcher velocity/penetration data is very interesting. First; I have pasted the graphs for the two general types of penetration behavior, based on pellet velocity directly below:
Non-deforming round ball (BB) penetration appears very linear with velocity. Both increasing the velocity and mass (lead VS steel) increases penetration proportionately. Thus, penetration is proportional to projectile momentum for robust projectiles of this shape:
(http://www.brassfetcher.com/images/0.172%20steel%20and%20lead%20sphere.png)
The link shows the penetration VS velocity graphs for a number of other pellets. The RWS wadcutters graph below demonstrate how pellets that are or become blunt (deform) behave with increasing velocity. This tendency for penetration to increase with velocity, then to drop off sharply after peaking includes "round nose" and "sharp point" pellets, that do not have (hemi)spherical heads (with tangent nose radii).
(http://www.brassfetcher.com/images/8.2gr%20wadcutter.png)
The consolidated data graph below indicates that the 8 grain lead BB penetrated better than the 8 grain round nose diabolo pellet. Here, momentum appears less important than form (or deformation at higher velocity):
(http://www.brassfetcher.com/images/All%20177%20caliber%20pellet.png)
Considering the above, you might say; "we are both right"...
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The brassfetcher velocity/penetration data is very interesting. First; I have pasted the graphs for the two general types of penetration behavior, based on pellet velocity directly below:
Non-deforming round ball (BB) penetration appears very linear with velocity. Both increasing the velocity and mass (lead VS steel) increases penetration proportionately. Thus, penetration is proportional to projectile momentum for robust projectiles of this shape:
(http://www.brassfetcher.com/images/0.172%20steel%20and%20lead%20sphere.png)
The link shows the penetration VS velocity graphs for a number of other pellets. The RWS wadcutters graph below demonstrate how pellets that are or become blunt (deform) behave with increasing velocity. This tendency for penetration to increase with velocity, then to drop off sharply after peaking includes "round nose" and "sharp point" pellets, that do not have (hemi)spherical heads (with tangent nose radii).
(http://www.brassfetcher.com/images/8.2gr%20wadcutter.png)
The consolidated data graph below indicates that the 8 grain lead BB penetrated better than the 8 grain round nose diabolo pellet. Here, momentum appears less important than form (or deformation at higher velocity):
(http://www.brassfetcher.com/images/All%20177%20caliber%20pellet.png)
Considering the above, you might say; "we are both right"...
I'd definitely say, that momentum does indeed matter, and energy is not the key to penetration by any means. But, I never said energy doesn't matter. It's the easiest way to determine if you have enough power to ensure a clean kill. When it comes to more powerful rifles and bigger animals, everything changes. Bullet construction becomes far more important as velocity increases.
To be fair, the lead round ball has much more energy at a given velocity than a steel bb. It's nit just the momentum, obviously.
One thing we can agree on, more power generally yields more penetration with a given projectile, until you push it so hard that it comes apart.
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The results are pretty much in agreement with theory.... The roundballs do not deform at the velocities used, so penetration is proportional to velocity and SD (ie momentum)…. If the projectile expands or tumbles, all bets are off, because the EFFECTIVE SD changes (same mass, larger area)…. Yes, shape makes a huge difference, just like it does in air, lending credence to the concept I have talked about in the past of a "flesh BC" which works in a similar manner to the BC in air.... the slipperier the shape, the better the penetration, the energy bleeds off at a slower rate, just like in air....
In a consistent medium, when comparing non-expanding projectiles of the same shape, penetration is proportional to the product of the velocity and SD.... That means that for a given caliber, it is proportional to the momentum.... The best example of this is the roundball…. The actual penetration depends on the medium chosen and the shape of the projectile as well....
Bob
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Also some interesting high speed photos and videos http://www.brassfetcher.com/Airguns/Airguns.html (http://www.brassfetcher.com/Airguns/Airguns.html)
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The roundballs do not deform at the velocities used, so penetration is proportional to velocity and SD (ie momentum)
OK. Does this mean that the 5 grain steel BB should penetrate as far as the 8 grain lead BB when their momentums are equal; as in, their velocities are as follows, respectively?
800 and 500 FPS
1200 and 750 FPS
Do the approximately 8 and 10% differences from parity in penetration (favoring the steel ball) suggest the lead ball is actually deforming a little? Or, perhaps that the steel ball is smoother (or slightly smaller in diameter) and has lower drag on the gel.
Another possibility is that the tester used the approximate weights for the pellets, rather than actual. The RWS wadcutters are shown as "8 grain", when the cans they come in list them as 8.2 grain. Similarly, the CPL round nose pellets are actually 7.9 grain. Perhaps the lead BBs were not actually 8 grains in weight.
EDIT: Gamo lead BB is listed as 8.2 grains; while steel BBs are listed at 5.1 grain:
https://www.pyramydair.com/product/gamo-177-cal-8-2-grains-round-lead-balls-250ct?p=78 (https://www.pyramydair.com/product/gamo-177-cal-8-2-grains-round-lead-balls-250ct?p=78)
https://www.pyramydair.com/product/copperhead-177-cal-5-1-grains-bbs-1500ct?p=106 (https://www.pyramydair.com/product/copperhead-177-cal-5-1-grains-bbs-1500ct?p=106)
https://www.pyramydair.com/product/marksman-premium-grade-steel-bbs-5-1-grains-speedloader-1-300ct?p=439 (https://www.pyramydair.com/product/marksman-premium-grade-steel-bbs-5-1-grains-speedloader-1-300ct?p=439)
(http://www.brassfetcher.com/images/0.172%20steel%20and%20lead%20sphere.png)
Anyway, you have me convinced about momentum driving penetration. At least, for non deforming round BBs. This explains why round steel BBs are used to calibrate ballistic gel before testing real bullets:
https://www.instructables.com/id/Ballistics-Gel-Step-by-Step-Regulation-Testing-Den/ (https://www.instructables.com/id/Ballistics-Gel-Step-by-Step-Regulation-Testing-Den/)
http://www.policemag.com/channel/weapons/articles/2004/06/bang-for-the-buck-how-to-make-ballistic-gelatin.aspx (http://www.policemag.com/channel/weapons/articles/2004/06/bang-for-the-buck-how-to-make-ballistic-gelatin.aspx)
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IMO 8-10% correlation with theory on single tests is pretty close.... If you tested 10 shots, and then drew a trendline through all the datapoints it may well be even closer.... It is interesting that the steel BB has a slight edge, whereas if higher velocity was a detriment (as suggested earlier) it should be the reverse.... There is a good possibility that the diameter of the BBs are not identical either.... The steel BB has to be small enough to pass along the lands, whereas a lead roundball may well be large enough to engage the rifling.... We would need to know both the exact diameters and weights before trying to nitpik that last few percent....
I can't take credit for the "Penetration is proportional to SD x Velocity" formula.... It comes straight of the Penetration calculator used in ChairGun…. However, the testing I have done seems to follow it pretty closely.... certainly close enough when you consider the different densities of an animal that a pellet/bullet encounters....
Bob
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IMO 8-10% correlation with theory on single tests is pretty close.... If you tested 10 shots, and then drew a trendline through all the datapoints it may well be even closer.... It is interesting that the steel BB has a slight edge, whereas if higher velocity was a detriment (as suggested earlier) it should be the reverse.... There is a good possibility that the diameter of the BBs are not identical either.... The steel BB has to be small enough to pass along the lands, whereas a lead roundball may well be large enough to engage the rifling.... We would need to know both the exact diameters and weights before trying to nitpik that last few percent....
I can't take credit for the "Penetration is proportional to SD x Velocity" formula.... It comes straight of the Penetration calculator used in ChairGun…. However, the testing I have done seems to follow it pretty closely.... certainly close enough when you consider the different densities of an animal that a pellet/bullet encounters....
Bob
Hardness and construction, steel vs. lead. Like barnes vs. standard cup and core. The lead bb may deform very little, but the steel holds together so well you can probably shoot it again.
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Irrelevant, really.... The theory is for non-deforming projectiles....
Bob
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Irrelevant, really.... The theory is for non-deforming projectiles....
Bob
The theory, yes. But in practice, the lead sphere does indeed deform. At the same power level, vs. velocity, hardness is irrelevant? If you are going to "nit pick"...
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I re-plotted some of the Brassfetcher data to look at the momentum and energy dependency. I was lazy so I used the tabular data which looks to be from a curve fit. It varies a little from what I assume to be test points on their plots.
1) Re-plot of the velocity for the 2 round balls, domed, and pointed pellets
2) Penetration Vs. momentum (used simple gr ft/s units)
3) Penetration Vs. momentum/area I used the expanded diameter listed
4) Penetration Vs. energy (w x V2)/450240
5) penetration Vs. Energy/area I used the expanded diameter
I think field experience (which I don't have) trumps anything drawn from these.
In my thinking, the pellet arrives with energy and all of the losses in the ballistic gel are energy terms. Unfortunately the drag is a V2 term as is the initial energy so you don't see the usual energy-distance curve. Actually there are reports that the gel response varies with velocity.
In real life, the energy loss in the hide and any bone impact would need to be included and may change the rankings in this data.
Interesting thought exercise though.
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Interesting data manipulation, Stan.
Now, if we could plot the volume of combined temporary and permanent cavity, and plot that against FPE; I predict a straight line....
Ballistic gel snaps back, so there is no way to capture the temporary cavity; except in 2D via high speed video. Soap and clay might be useful here because their cavities do not collapse (unless you blow up the block), but how to measure the volume of the cavity? Perhaps by casting epoxy or plaster of paris into it.
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I should know better, by now, than to even comment on these things. Why do I even bother? It's click bait!
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Bryan, I didn't meant the comment was irrelevant, you are 100% correct, hardness is important as it affects the deformation of a projectile.... I meant that such deformation is impossible to allow for with simple penetration theories....
subscriber, you are correct, there is a definite correlation between the volume of the wound channel and the FPE.... While the penetration is more related to the momentum, given equal momentum a projectile with more energy (which for a given caliber means it is lighter and travelling faster) will generally create a larger (diameter) wound channel.... My "calibrated eyeball" tells me that wound cavities in soap are approximately proportionate to the impact energy.... Whether that approximation is within 20% or 100% I have no idea.... It seems to roughly apply to comparing, for example, HP bullets to FN bullets (same shape before expansion) at the same energy....
Bob
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Now, if we could plot the volume of combined temporary and permanent cavity, and plot that against FPE; I predict a straight line....
As an aside, I found this paper which used a high speed camera to measure the velocity decay in BG. They also captured the size and shape of the temporary and permanent cavities. Unfortunately it is 9mm PB, but still interesting.
https://arxiv.org/ftp/arxiv/papers/1305/1305.5215.pdf (https://arxiv.org/ftp/arxiv/papers/1305/1305.5215.pdf)
If someone has a 20000 frames/sec camera, I'll spring for the Jello......
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I'm seeing a different approach when planning to hunt hogs.
In the specific case of forehead shots, the pellet has to overcome the bone. Btw, from a study with domestic pigs (same species), I would guess that up to "10" mm of this bone thickness would be representative of feral hogs up to "110" pounds.
I presume it would not be a pure penetration task, but, just a little bit of penetration, continued by the decisive break through.
And the original intention of the question is reopened - momentum or fpe?
Perhaps, to quickly jump to what does really matter, would it be better a hollow point?
http://cdn.intechopen.com/pdfs/21043/InTech-Biomechanical_characteristics_of_the_bone.pdf (http://cdn.intechopen.com/pdfs/21043/InTech-Biomechanical_characteristics_of_the_bone.pdf)
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Marcos,
I think you may have to go to a butcher and get one or two hog heads for testing. It will be difficult to find a ballistic test equivalent to help you choose HP or solid. The bone strength studies such as the one you posted or this one https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090900/ (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090900/) look primarily at bone tension/compression strength (for breakage and blunt force) but your situation may emphasize shear strength (puncture). You would also need to have the hide present (a pigskin motorcycle jacket I had always took less damage than I did when tested ;D).
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Or if you want to make a project of it (and scare your neighbors) try this one https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491591/ (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491591/)
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You could just ask Manny (Nomadic Pirate) about penetration of a hog's skull. I would place my bets on the heaviest dome pellet your rifle likes.
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Stan, by now, I am disconsidering the hide (as a 'no problem'). If I was in the game about 25 years ago, among other things, I was also a pig farmer .. Besides several tests, I would have made a table with the weights and thicknesses of the forehead bones.
Dreams out, I agree with you - the main task seems to be about the .. shear strenght.
In my current 'urban environment', there are not pig heads available. I tried with cattle leg bones using some 'promising' pellets (domed/heavier or with the harder heads) at short distance (2 yards?); not 100% perpendicular due the ricochets, but 'enough' angle. You may consider zero 'damage' and all became flat flowers of lead.
Bryan, Manny and his big bores don't have this kind of problem.. The challenge is when you start thinking about the actual limit to be, or not to be .. undergunned. By now, until an eventual better idea .. I'm with you, and placing my bets on the JSB Straton Jumbo Monster 25 gr (just a little bit "pointed").
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Stan, by now, I am disconsidering the hide (as a 'no problem'). If I was in the game about 25 years ago, among other things, I was also a pig farmer .. Besides several tests, I would have made a table with the weights and thicknesses of the forehead bones.
Dreams out, I agree with you - the main task seems to be about the .. shear strenght.
In my current 'urban environment', there are not pig heads available. I tried with cattle leg bones using some 'promising' pellets (domed/heavier or with the harder heads) at short distance (2 yards?); not 100% perpendicular due the ricochets, but 'enough' angle. You may consider zero 'damage' and all became flat flowers of lead.
Bryan, Manny and his big bores don't have this kind of problem.. The challenge is when you start thinking about the actual limit to be, or not to be .. undergunned. By now, until an eventual better idea .. I'm with you, and placing my bets on the JSB Straton Jumbo Monster 25 gr (just a little bit "pointed").
Manny hasn't always used big bores. He has been killing pigs with .22 and .25 air rifles longer than most of us have been serious about air guns in general. Maybe you should look back into the archives, or just ask him. From what I have seen in the hunting gate, heavy dome pellets are the clear winner on hogs with a typical small bore airgun. In my own experience hunting small game, heavy domes still win. And if you take the time to search the googles, people have figured out a very long time ago, within a given caliber, the heaviest projectile penetrates the best. Blackpowder, smokeless powder, air power- doesn't matter. Until you push it so fast that the bullet comes apart, then you have to use harder material. But that is the way it is. Heavy, accurate, domes- that is your common money maker. Other than a slug, cylinder, or roundball. But dome diabolos are more common, more likely to find one your gun shoots straight...
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What a great discussion!
Yeah, Bryan, I agree, this kind of stuff is clickbait for some of us! ::)
...educational clickbait...
And I keep clicking...
...because I like to be educated.
(((Or I just got bitten by the airgun bug...!))) ;D
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Interesting data manipulation, Stan.
Now, if we could plot the volume of combined temporary and permanent cavity, and plot that against FPE; I predict a straight line....
Ballistic gel snaps back, so there is no way to capture the temporary cavity; except in 2D via high speed video. Soap and clay might be useful here because their cavities do not collapse (unless you blow up the block), but how to measure the volume of the cavity? Perhaps by casting epoxy or plaster of paris into it.
Water will work well for that.
a simple large syringe, fill with water and use that to fill the cavity, keeping track of how much water you put in it till its full. it'll work well enough to get an idea of the volume of the cavity, provided the pellet/bullet didn't exit the medium.
or if you want something to show greater detail of the cavity I suppose colored gelatin can be used instead, and just let it set & cut it out after, but there may be some contraction of the gelatin or medium while they're being cooled for the gelatin to set.
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Water will dissolve soap, and may also contaminate it for remelt and further use.... I don't know about clay.... From what I have seen of the cavities in clay, they seem to be much larger than what we see in reality with game.... JMHO....
Bob
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Stan, by now, I am disconsidering the hide (as a 'no problem'). If I was in the game about 25 years ago, among other things, I was also a pig farmer .. Besides several tests, I would have made a table with the weights and thicknesses of the forehead bones.
Dreams out, I agree with you - the main task seems to be about the .. shear strenght.
In my current 'urban environment', there are not pig heads available. I tried with cattle leg bones using some 'promising' pellets (domed/heavier or with the harder heads) at short distance (2 yards?); not 100% perpendicular due the ricochets, but 'enough' angle. You may consider zero 'damage' and all became flat flowers of lead.
Bryan, Manny and his big bores don't have this kind of problem.. The challenge is when you start thinking about the actual limit to be, or not to be .. undergunned. By now, until an eventual better idea .. I'm with you, and placing my bets on the JSB Straton Jumbo Monster 25 gr (just a little bit "pointed").
Manny hasn't always used big bores. He has been killing pigs with .22 and .25 air rifles longer than most of us have been serious about air guns in general. Maybe you should look back into the archives, or just ask him. From what I have seen in the hunting gate, heavy dome pellets are the clear winner on hogs with a typical small bore airgun. In my own experience hunting small game, heavy domes still win. And if you take the time to search the googles, people have figured out a very long time ago, within a given caliber, the heaviest projectile penetrates the best. Blackpowder, smokeless powder, air power- doesn't matter. Until you push it so fast that the bullet comes apart, then you have to use harder material. But that is the way it is. Heavy, accurate, domes- that is your common money maker. Other than a slug, cylinder, or roundball. But dome diabolos are more common, more likely to find one your gun shoots straight...
Ok wait. I've read over this before, but somehow this information is only starting to hit me now. ???
So a heavier pellet in the same caliber, despite having less FPE, will penetrate better?
For example: a CPUM Dome at 14.3 at ~ 28FPE will be out-penetrated by say an ~23-24FPE Baracuda Match 21gr?
I seem to have been under the impression that my FPE will be most beneficial to breaking through that hog skull, i.e. the higher the better.
Have I been doing it wrong all along?
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Stan, by now, I am disconsidering the hide (as a 'no problem'). If I was in the game about 25 years ago, among other things, I was also a pig farmer .. Besides several tests, I would have made a table with the weights and thicknesses of the forehead bones.
Dreams out, I agree with you - the main task seems to be about the .. shear strenght.
In my current 'urban environment', there are not pig heads available. I tried with cattle leg bones using some 'promising' pellets (domed/heavier or with the harder heads) at short distance (2 yards?); not 100% perpendicular due the ricochets, but 'enough' angle. You may consider zero 'damage' and all became flat flowers of lead.
Bryan, Manny and his big bores don't have this kind of problem.. The challenge is when you start thinking about the actual limit to be, or not to be .. undergunned. By now, until an eventual better idea .. I'm with you, and placing my bets on the JSB Straton Jumbo Monster 25 gr (just a little bit "pointed").
Manny hasn't always used big bores. He has been killing pigs with .22 and .25 air rifles longer than most of us have been serious about air guns in general. Maybe you should look back into the archives, or just ask him. From what I have seen in the hunting gate, heavy dome pellets are the clear winner on hogs with a typical small bore airgun. In my own experience hunting small game, heavy domes still win. And if you take the time to search the googles, people have figured out a very long time ago, within a given caliber, the heaviest projectile penetrates the best. Blackpowder, smokeless powder, air power- doesn't matter. Until you push it so fast that the bullet comes apart, then you have to use harder material. But that is the way it is. Heavy, accurate, domes- that is your common money maker. Other than a slug, cylinder, or roundball. But dome diabolos are more common, more likely to find one your gun shoots straight...
Ok wait. I've read over this before, but somehow this information is only starting to hit me now. ???
So a heavier pellet in the same caliber, despite having less FPE, will penetrate better?
For example: a CPUM Dome at 14.3 at ~ 28FPE will be out-penetrated by say an ~23-24FPE Baracuda Match 21gr?
I seem to have been under the impression that my FPE will be most beneficial to breaking through that hog skull, i.e. the higher the better.
Have I been doing it wrong all along?
Not really. Just a couple of things to remember:
Penetration matters more as your game gets bigger. Energy is still the figure we usually refer to, in order to determine if you have enough gun.
Heavy typicallypenetrates better than light, for a given caliber, at the same energy level. Of course the shape of the ammo also makes a difference.
Naturally, that means you can have a little less energy and still equal to or better penetration with a heavy for caliber round.
Penetration isn't everything. But given a choice, I'd rather have an exit. Especially with small bore airguns. 2 holes are better than one, and exit wounds usually bleed better than entrance wounds. More bleeding means a animal expires faster, suffers less.
Yeah, a bigger hole also bleeds better than a smaller one. But if you really wanna argue wound channel, well, .177 x2 is bigger than .22 x1. And again, exits bleed better than a entrance wound. Usually bigger coming out as well. Especially considering airgun power levels, ammo generally retains weight except a few designs.
Still, given a choice between 10 fpe and 10.5 grains vs 15 fpe at 7.9 grains, I'll take the higher energy level.
The thing is, with a springer a heavy pellet may deliver 5% less energy give or take. We are talking 13 fpe vs 14-14.5 fpe. The 10.5 grain will outpenetrate!
You can go back and forth on this all day. At the end of the day, 3 things still hold true, that most of us can agree on:
1. We usualy look at energy levels and accuracy to determine if a gun is adequate for hunting.
2. Heavier ammo generally penetrates better than lighter ammo.
3. Pneumatics generally make more energy and momentum with heavier pellets. Exception being, ammo with more friction in the bore (harder, maybe head size,etc.) Springers usually make less energy with heavier pellets.
Regardless, it is kinda making a big deal out of nothing. I would not hesitate to make a headshot on a raccoon, possum, armadillo, etc with any pellet design inside of my comfortable range with a mid powered springer even with a wadcutter. .22 or .177. Talking 25 yards give or take.
The Sheridan? Especially a Steroid Streak... whatever is accurate is going to get the job done, on anything a reasonable airgunner would try.
I gotta quit clicking on this thread... so tempting...
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I gotta quit clicking on this thread... so tempting...
Bryan, don't we love this click bait?! ;)
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I gotta quit clicking on this thread... so tempting...
Bryan, don't we love this click bait?! ;)
Sure do :)
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Stan, by now, I am disconsidering the hide (as a 'no problem'). If I was in the game about 25 years ago, among other things, I was also a pig farmer .. Besides several tests, I would have made a table with the weights and thicknesses of the forehead bones.
Dreams out, I agree with you - the main task seems to be about the .. shear strenght.
In my current 'urban environment', there are not pig heads available. I tried with cattle leg bones using some 'promising' pellets (domed/heavier or with the harder heads) at short distance (2 yards?); not 100% perpendicular due the ricochets, but 'enough' angle. You may consider zero 'damage' and all became flat flowers of lead.
Bryan, Manny and his big bores don't have this kind of problem.. The challenge is when you start thinking about the actual limit to be, or not to be .. undergunned. By now, until an eventual better idea .. I'm with you, and placing my bets on the JSB Straton Jumbo Monster 25 gr (just a little bit "pointed").
Manny hasn't always used big bores. He has been killing pigs with .22 and .25 air rifles longer than most of us have been serious about air guns in general. Maybe you should look back into the archives, or just ask him. From what I have seen in the hunting gate, heavy dome pellets are the clear winner on hogs with a typical small bore airgun. In my own experience hunting small game, heavy domes still win. And if you take the time to search the googles, people have figured out a very long time ago, within a given caliber, the heaviest projectile penetrates the best. Blackpowder, smokeless powder, air power- doesn't matter. Until you push it so fast that the bullet comes apart, then you have to use harder material. But that is the way it is. Heavy, accurate, domes- that is your common money maker. Other than a slug, cylinder, or roundball. But dome diabolos are more common, more likely to find one your gun shoots straight...
Ok wait. I've read over this before, but somehow this information is only starting to hit me now. ???
So a heavier pellet in the same caliber, despite having less FPE, will penetrate better?
For example: a CPUM Dome at 14.3 at ~ 28FPE will be out-penetrated by say an ~23-24FPE Baracuda Match 21gr?
I seem to have been under the impression that my FPE will be most beneficial to breaking through that hog skull, i.e. the higher the better.
Have I been doing it wrong all along?
Not really. Just a couple of things to remember:
Penetration matters more as your game gets bigger. Energy is still the figure we usually refer to, in order to determine if you have enough gun.
Heavy typicallypenetrates better than light, for a given caliber, at the same energy level. Of course the shape of the ammo also makes a difference.
Naturally, that means you can have a little less energy and still equal to or better penetration with a heavy for caliber round.
Penetration isn't everything. But given a choice, I'd rather have an exit. Especially with small bore airguns. 2 holes are better than one, and exit wounds usually bleed better than entrance wounds. More bleeding means a animal expires faster, suffers less.
Yeah, a bigger hole also bleeds better than a smaller one. But if you really wanna argue wound channel, well, .177 x2 is bigger than .22 x1. And again, exits bleed better than a entrance wound. Usually bigger coming out as well. Especially considering airgun power levels, ammo generally retains weight except a few designs.
Still, given a choice between 10 fpe and 10.5 grains vs 15 fpe at 7.9 grains, I'll take the higher energy level.
The thing is, with a springer a heavy pellet may deliver 5% less energy give or take. We are talking 13 fpe vs 14-14.5 fpe. The 10.5 grain will outpenetrate!
You can go back and forth on this all day. At the end of the day, 3 things still hold true, that most of us can agree on:
1. We usualy look at energy levels and accuracy to determine if a gun is adequate for hunting.
2. Heavier ammo generally penetrates better than lighter ammo.
3. Pneumatics generally make more energy and momentum with heavier pellets. Exception being, ammo with more friction in the bore (harder, maybe head size,etc.) Springers usually make less energy with heavier pellets.
Regardless, it is kinda making a big deal out of nothing. I would not hesitate to make a headshot on a raccoon, possum, armadillo, etc with any pellet design inside of my comfortable range with a mid powered springer even with a wadcutter. .22 or .177. Talking 25 yards give or take.
The Sheridan? Especially a Steroid Streak... whatever is accurate is going to get the job done, on anything a reasonable airgunner would try.
I gotta quit clicking on this thread... so tempting...
ok...so that Baracuda Match 21gr at about 24FPE will give penetration similar to the 14.3gr CPUM Dome at 28FPE? I have some 18gr Baracuda Extremes, but I'm not exactly confident about hollow points being able to use their energy to penetrate bone. My friend that I junglewalk with swears that HPs are the best round for the smaller calibers. For me I kinda differ on that opinion, all things granted. I won't be taking body shots with a .22LR...those will all be head shots. So if it's a headshot, I would think the solid point would be better.
That being said, I would trust the Domes or Baracuda Match more for a headshot. I hear you about wound channels and exit wounds, but for my application, I think I'll be ok as long as I can get into that brainpan. Now if I can get a complete pass through (although I think that would be a little difficult on those larger 30+ pound pigs) that would be awesome, but I'm quite aware that I'm only working with a springer. I shoot extensively at 20-30 yards because that is pretty much the effective range for Maggie, considering the quarry that I have in mind.
Lol...I don't mean to add to the clickbait. It was a honest concern. 8)
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Brainshots are different, blood not a factor really.
Youll have to do that penetration test and get back to us
At the exact same power level barracudas will drive deeper than any 14 grain ammo. But you would have to experiment to find out how much lower you can go And achieve desried results
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I'll need to do another 2x4 test with the CPUM Domes, Copper CPUMs, Gamo Rockets, Baracuda Extremes and the Baracuda Match.
The previous test I ran, I didn't include the Domes. Now I have the Copper Domes and the Piranhas as well, so it should be interesting. The biggest obstacle will be finding the proper medium that most closely simulates bone. The only penetration test I did was using a 2x4 at 20 yards; I was getting about an inch deep.
I guess I can grab a 1/2-3/4" piece of plywood and another piece of 2x4...but what would closest resemble bone? Butcher shops here don't sell skulls. :(
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The problem with wood is that the grain drastically alters the penetration.... Consistency is almost impossible to achieve with it.... so comparisons are pretty doubtful....
Bob
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:( Great.
Soooo....I'm off to research another medium. I heard a coconut is a decent comparison, but can you imagine the ricochets?
How about a sheet of metal? Certain thickness to compare to how hard it would be to penetrate through bone? Wet phone book? Plastic? Stick of dynamite?
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I think, based on some of the research links posted earlier, it is hard to come up with a simulation of the hog head. If you can't get one from a hunter or a slaughterhouse, maybe you can compare pellets using a more uniform, hard material like masonite or something like that. It may tell you which pellet is better but you won't know if it is good enough.
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I think a phone book, wet or dry, should be a good place to start. You get to see the difference between measuring from entrance to the back of the skirt vs depth of the nose of the pellet. I think you will find that usually a heavy pellet will have a shallower hole to the back of the skirt, in a dense medium like wood, but you have to cut it to see the actual depth of the nose. Using a phone book, you can count the pages easily.
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I think, based on some of the research links posted earlier, it is hard to come up with a simulation of the hog head. If you can't get one from a hunter or a slaughterhouse, maybe you can compare pellets using a more uniform, hard material like masonite or something like that. It may tell you which pellet is better but you won't know if it is good enough.
Thanks, WhatUPSbox. I'll take a look at the Masonite. There's been a little piggy roaming around near the inlaw's place...probably about 15-20lbs. He's gonna be real nice some bbq.
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I think a phone book, wet or dry, should be a good place to start. You get to see the difference between measuring from entrance to the back of the skirt vs depth of the nose of the pellet. I think you will find that usually a heavy pellet will have a shallower hole to the back of the skirt, in a dense medium like wood, but you have to cut it to see the actual depth of the nose. Using a phone book, you can count the pages easily.
Thanks Bryan. I got some of those laying around, so maybe over the weekend I'll try some tests. 10, 15, 20, 25 and 30 should make real nice.
Got some 21gr Baracuda Match, 18gr Extreme, CPUM regular lead and copper and Piranhas, and the 15.6(?) grain H&N FTTs.
I also got some 28gr NSA HP boattails, but those are a softer lead. Eh...I guess I can throw those in anyways just for kicks.
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The phone book gives you good consistent results to compare by, but may give abnormal results with those NSA hollowpoints (or any hollowpoints) because those work in tissue. They may drive deep in dry phone books or wood, where they may expand more and penetrate less in the wet phone books.
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Hopefully the gel shot video I just produced will reveal some interesting concepts in pellet design.
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Any estimate of penetration quickly goes out the window as soon as the projectile expands or tumbles, of course.... I look forward to seeing your video....
Bob
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I just re-read this thread.
Honest, enticing click bait.Wonderful!! ;D
Now I want more.
Wasn't someone going to do a vid?
We talked about shooting hogs? Did you kill any?
Tell the tale how it went (or why it didn't go)!
Matthias
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Perhaps hanging the rifle from a rope as a Ballistics Pendulum would be educational?.... It would certainly be entertaining.... 8)
Can't be worse than a Garand ;)
(https://i.imgur.com/gYcx08W.gif)
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Yesterday I shot a large eggplant and only expected a hole in front and one in back, obviously. This seems relevant to the discussion and I was shocked to find that it was a not a total pass-through.
Scenario:
Predator Poly Mag .25 cal at 940fps and 17 yards
Outcome:
Not a pass-through shot but VERY large 'wound' channel and great expansion of the pellet head. It was a perfect shot, as it relates to killing eggplant, because it dumped ALL of its energy into the 'critter'.
I just posted my own thread but the pics seems useful here too.