Penetration and Expansion Testing

[rsterne]

Every once in a while I try and find a new test medium for assessing pellets.... Over the years I've tried, wood, phonebooks, paraffin wax (all too hard), water, plumbers putty, playdoh, and ballistics gel (IMO all too soft and/or temperature sensitive), and I recently tried a bar of clear soap, which showed promise, so I ordered some melt-and-pour soap online, and after a few initial test shots, cast it into some bricks for pellet testing.... I cast the bricks in 8 x 8 square Pyrex dishes, about 1.5" thick, and using my Grouse gun, shot into the edge of the bricks.... This gun shoots at 20 FPE quite consistently over 16 shots, with lighter pellets achieving about 19 FPE and heavy ones about 21 FPE, which is typical for a PCP.... Here are the results, and some observations....

Top row right to left:
Gamo Match Wadcutter 13.7 gr.
Gamo Hunter Domed 15.1 gr.
Gamo Magnum Pointed 15.1 gr.
Gamo Roundball 15.1 gr.
Gamo Master Point 16.4 gr.
Gamo TS-22 Rounded Point 21.6 gr.
Hatsan Domed 14.3 gr.
Predator Big Boy Pointed 26.0 gr.
The wadcutter shortened and expanded slightly, and had the least penetration.... The roundball left a very narrow wound channel, as did the TS-22 which penetrated deeply....



Bottom row, left to right:
RWS Hobby 11.9 gr. Wadcutter
RWS MeisterKugeln 14.0 gr. Wadcutter
RWS Super Hollow Point 14.3 gr.
RWS Super Dome 14.3 gr.
RWS Super Point 14.3 gr.
Crosman Wadcutter 14.3 gr.
Crosman Premier 14.3 gr.
Crosman Premier Hollow Point 14.3 gr.
The wadcutters, in particular the Hobby, showed some shortening and expansion, with a slightly wider initial wound channel.... The RWS Hollow Point stripped off the nose ring, leaving the aft part to penetrate, and left a larger wound channel where the nose stripped off just after entry.... The Crosman Premier Hollowpoint acted basically like it was a roundnose....

Second photo, top row, right to left:
H&N FTT Round Wadcutter 15.7 gr.
H&N Crow Magnum Hollow Point 18.0 gr.
H&N Baracuda Rounded Point 21.0 gr.
H&N Baracuda Power Rounded Point, Plated, 20.7 gr.
H&N Baracuda Hunter Hollow Point 18.2 gr.
H&N Baracuda Hunter Extreme Cross Point 19.1 gr.
EunJin Pointed 32.1 gr.
EunJin Domed 28.4 gr.
H&N Rabbit Magnun 24.8 gr. (underneath, see below)
The Crow Magnum, Hunter, and Hunter Extreme all mushroomed well and created large, shallow wound channels....



Bottom Row, left to right:
JSB Exact RS 13.4 gr.
JSB Exact Express 14.3 gr.
JSB Exact Jumbo 15.9 gr.
JSB Exact Heavy 18.1 gr.
JSB Exact Monster 25.4 gr.
JSB Straton Pointed 15.7 gr.
JSB Predator Polymag 16.2 gr.
(pellet escaped through side of block)
H&N Hollow Point 12.2 gr.
H&N FTT Round Nose 14.2 gr.
The JSB Pellets penetrated in order of their weight, as expected.... The Predator Polymag left the plastic tip behind and the front of the body folded back over the rest, leaving a wide wound channel.... The H&N Hollowpoint didn't expand, acting like a wadcutter....



This additional photo, from the other side of the second block, shows the EunJins and the Rabbit Magnum better.... The Rabbit Magnum (on the left)easily penetrated further than anything else, but left a very narrow wound channel.... It actually was quite a bit below the JSB RS pellet in the block, so they didn't affect each other....

Conclusions.... Generally speaking, from the same gun, heavier pellets of similar shape penetrate deeper.... There appears to be little difference in penetration between round nose (including the Crosman Premier HP) and pointed pellets of similar weight.... They all leave relatively narrow, tapered wound channels, and the pellet has little expansion or distortion in this medium.... Wadcutters (and the H&N 12.2 gr. Hollow Point) do not penetrate as far, and the initial part of the wound channel is larger in diameter, but again it is cone shaped, just wider and shallower.... The roundball and the bullet-shaped Rabbit Magnum left very long, narrow, nearly parallel-sided wound channels.... The H&N Crow Magnum expanded violently, leaving a short, wide wound channel, as did the two Baracuda Hunter Hollowpoints, the JSB Predator Polymag, and the RWS Hollowpoint.... All five of these hollowpoints left a bulge just after entry, where the expansion occurred....

I am extremely pleased with these results, not only because they seem to agree with our experiences of how pellets perform on game.... but also because of the clearly visible wound channel which is easy to photograph.... The shallowest penetration was the Crow Magnum at 39mm (1.5"), and the deepest was the Rabbit Magnum at 126 mm (5.0").... The series of five JSB Exacts started at 79 mm for the 13.4 gr. and went to 106 mm for the 25.4 gr. (3.1 - 4.2").... I think those are pretty realistic numbers for a 20 FPE gun, perhaps a bit low, but maybe pretty accurate for a combination of hide, muscle, and bone.... It's certainly in the ballpark, which means this medium is great for testing with....

Bob

[remtom1200]

Very interesting how the predator rolled back to a mushroom, and I'm not surprised with the CPHP. This was a great test Bob thank you.

[rsterne]

Good prediction.... and I agree.... depending on how fast I push them, of course.... What leaves me wondering is why their velocity and energy is so low in this rifle.... I didn't see that in my quarterbore Disco with a LW barrel.... they had higher FPE as would be expected of a heavier bullet....

Bob

[rsterne]

OK, so today I did more Non-PAL testing, in .22 cal, at a range of 25 yards.... I was using a 2289 tuned for 498 fps with JSB Exact RS 13.4 gr. pellets, and it shoots 485 fps with 14.3 gr Exact Express.... I didn't measure the velocity with lighter and heavier pellets, but they are what they are, just as they would be with any Non-PAL gun.... Since the soap was set up at 25 yards, I figured 1.25" of soap was enough to stop the pellets, but I very nearly got pass throughs with all of the JSB Exacts, and the H&N Baracuda, they all bulged the far side of the block of soap.... Here are photos of both sides of the block....





I "flipped" the photo of the back so that the pellets are in the same relative location in the block to make it easy to find them.... Here is a list of the pellets by number, with the penetration in mm:

1. JSB Exact RS Round Nosed 13.4 gr. - 34 mm
2. JSB Exact Express Round Nosed 14.3 - 35
3. JSB Exact Jumbo Round Nosed 15.9 - 36
4. JSB Exact Heavy Round Nosed 18.1 - 35
5. JSB Exact Monster Round Nosed 25.3 - 38
6. H&N Baracuda Pointed Round 30.9 - 37
7. RWS Hobby Wadcutter 11.9 - 20
8. RWS Super HollowPoint Hollow Point 14.3 - 23
9. RWS Super Dome Domed 14.3 - 23
10. RWS Super Point Pointed 14.3 - 26
11. Crosman Wadcutter Wadcutter 14.3 - 18
12. Crosman Premier HP Round HP 14.3 - 29
13. Crosman Premier Round Nosed 14.3 - 30
14. H&N Hollow Point Hollow Point 12.2 - 17
15. H&N Field Target Trophy Round Nosed 14.2 - 28
16. H&N Crow Magnum Hollow Point 18.0 - 17
17. JSB Predator Polymag Tipped HP 16.2 - 22

There are a few important observations to be made.... First, there is little difference in the diameter of the entry wound, regardless of the pellet type.... In fact, the slight cratering that appears around some of the holes appears to be related more to the impact velocity than the pellet shape.... There was no cratering observed in pellets over 15 gr.... Secondly, the penetration was mostly related to the shape of the pellet.... There was also a close correlation between the Ballistics Coefficient and the penetration.... The pellets that penetrated the furthest had good BCs and arrived at the target with the largest percentage of their FPE remaining.... This is very much "real world" testing at its best.... Here are photos of the wound channels of all the pellets tested....















Note that none of the pellets showed ANY sign of expansion when recovered from the soap.... Their killing power is strictly a function of how deeply they penetrated, as there is no significant difference in the shape of the wound channel.... I didn't test every pellet I had available, but I feel that the cross section of pellets tested tells the story well.... For example, there was no point in testing heavy hollowpoints that didn't expand at more than twice these FPE levels.... I didn't test any .177 pellets, as they didn't fare as well as the .22 cal pellets in previous tests at non-PAL velocities....

In conclusion, I am convinced that with the meager energy available in a non-PAL airgun, delivering as much of that energy as possible to the target is the most important consideration when hunting.... That means that .22 is far superior to .177.... It means that round-nosed pellets are superior to any other shape because of their better BC and superior energy retention.... None of the pellets show any expansion, nor does "shocking power" appear to be an issue, particularly when you consider that the wadcutters and hollowpoints arrive at the target with less FPE because of their poorer BCs.... There is little difference in the penetration of different weights of round nosed pellets because the heavier ones start out slower.... Some of the heavy pellets required more than two Mil-Dots of holdover at just 25 yards, compared to a 14.3 gr. pellet, so trajectory becomes a big issue.... That brings us down to a very few choices, and the top two are the JSB Exacts in 13.4 gr. and 14.3 gr.... Next would be the Crosman Premier 14.3 gr. (including the HP) and the H&N FTT at 14.2 gr.... If your gun shoots any of those accurately, I would stop looking.... The RWS "Super" trio (HollowPoint, Domed, and Pointed) also at 14.3 gr are the remaining group to try.... If you want to try something just a bit heavier, the JSB Exact 15.9 gr. and Predator Polymag 16.2 gr. would fill out the field.... I wouldn't go any heavier because of trajectory considerations.... Personally, the only time I would use a wadcutter (or any of the other pellets) is if none of the above are accurate in your gun, and then you must reduce the range accordingly....

Bob

[pharoah007]

I wonder what the results for hollow points would show if there was a simulated "hide" over the soap.

I would think the initial expansion comes form hitting the harder "skin/Fur" outer before entering the soft guts/meat.

Mu guess would be more expansion and less penetration.

Maybee it is time to take a trip to GoodWill and buy a old fur for 5$ ;)

Just a thought.

[rsterne]

Here are the recovered pellets from the soap tests above.... These are the only ones that showed any noticeable distortion or expansion.... All the others looked like they could literally be reused....



Top row, left to right:
JSB Predator Polymag - shed the tip when it expanded
H&N Crow Magnum - violent expansion
H&N Baracuda Hunter - violent expansion
H&N Baracuda Hunter Extreme- violent expansion

Bottom row, left to right:
Crosman Wadcutter - barely shortened, no noticable expansion
Gamo Match - some shortening and minimal expansion
RWS Hobby - lightest pellet, highest velocity, significantly shortened and a bit of expansion
RWS MeisterKugeln - some shortening and minimal expansion
RWS Super Hollow Point - shed the ring around the head, and the rear portion penetrated deeply

The wadcutters decelerated very rapidly, causing a larger entry wound, but penetration suffered.... good shocking power at close range....

These hollowpiont designs all did their job, and did it well.... The Crosman Premier Hollowpoint and the H&N Hollowpoint (both made of harder materials, with very small cavities) basically didn't expand or show a large entry wound.... ie at this velocity, they weren't working as intended....

Bob

[rsterne]

They have no skirt, they are a flat-based bullet design.... It is curious, as they work normally in a LW barrel.... The bolt seal in these guns doesn't leak.... The only other thing that is different is the pressure, which in this gun is 1800 psi and in my Disco is much higher.... hmmmmmmmmmmm.... maybe that is the answer, not enough pressure to overcome the extra drag of the multiple driving bands.... Yeah, thinking on it, that's probably the culprit....

EDIT: Nope, it's not the pressure.... I checked my notes and achieved 75 FPE at 1600 psi while testing the Mr. HollowPoints in my Disco.... Weird !!!

Bob

[rsterne]

I purchased from here.... http://www.newdirectionsaromatics.ca...ear-p-598.html

I purchased the 12-pack of 2 lb. bricks.... It takes two bricks to fill an 8 x 8 x 2 Pyrex dish or a 9 x 5 x 3 loaf pan.... You melt it in a double boiler....

This is another source.... http://secure.mycart.net/catalogs/ca...showprevnext=1

I don't know if it's "the best", but it can be remelted and repoured whenever you want.... I would imagine those two products are the same....

Bob

[sholo]

Excellent test and review, Bob. Thanks for posting that!

I was a little surprised (and at the same time disappointed) that the Polymags didn't mushroom any more than that as they are the most accurate in my 2260 to date, although they apparently leave a nice wound channel.

Too bad the Crow Magnum doesn't group well in my gun, but luckily the Hunter's are quite accurate, and after hitting a few tree rats @ 31 fpe using them I can now see why they are so devastating - excellent mushrooming, plus, as your pic shows, with such shallow penetration that's a lot of energy being released in such a short distance.

Todd

[rsterne]

I did a few more tests today, with cast bullets at higher FPE levels.... I started by adding the data for the solid and hollowpoints I recently cast from the RCBS 50 gr. mold I purchased, shooting them from my 2560 regulated PCP, and once again, for whatever reason, the energy level is only about 40 FPE (instead of 50), similar to what I got with the Mr. Hollowpoints.... The bullets I cast weighed 52.7 gr. for the solid, and 46.4 gr. for the hollowpoint, and here are the results....



You can see that the solid penetrated within an inch of the far side of the block, easily the deepest penetration I had seen to date.... I shot 2 of the hollowpoints, on from each side, and they both penetrated a bit deeper than the Mr. Hollowpoints I tested at the same FPE level, leaving a small entry hole and a similarly shaped wound channel.... I then pulled out my .25 cal Disco, which shoots about 85 FPE, and tested the same two bullets, plus the 50.0 and 58.8 gr. Mr. Hollowpoints.... The first solid went right through the 8" block of soap, but I had a second block handy, so I turned the block 90* and shot through the other block to produce the channel coming from the right side in the photo below....



The channel from the right is the 52.7 gr. solid, after already penetrating 8" of soap in another block.... The tracks from the bottom, left to right are:

46.4 gr. Lyman hollowpoint
52.7 gr. Lyman solid (first shot, straight through the block)
50.0 gr. Mr. Hollowpoint
58.8 gr. Mr. Hollowpoint

You can see the huge wound cavities about an inch into the block where the hollowpoints exploded.... The block was bulged a lot right above those cavities, which measured between 3/4-1" across, and had numerous imbedded bullet fragments.... Here are photos of the recovered bullets....



Top row, left to right, all shot at 85 FPE:
46.4 gr. Lyman hollowpoint
50.0 gr. Mr. Hollowpoint
58.8 gr. Mr. Hollowpoint

Bottom row, left to right:
52.7 gr. Lyman solid shot at 85 FPE
52.7 gr. Lyman solid shot at 40 FPE
46.4 gr. Lyman hollowpoint shot at 40 FPE
repeat of above HP @ 40 FPE

In summary, the 52.7 gr. Lyman solid has easily the greatest penetration I have seen to date, 175 mm (6.9") at 40 FPE and 318 mm (12.5") at 85 FPE.... interestingly just about exactly proportional to the FPE level.... The 46.4 gr. Lyman hollowpoints I cast performed well at 40 FPE, mushrooming completely.... At 85 FPE, all the hollowpoints came apart, which really surprised me.... The velocities ranged from just over 800 to just over 900 fps, depending on bullet weight, and it just shows how much damage a hollowpoint can do at those impact velocities and energies.... If I want to test anything over 100 FPE, I'm going to need bigger blocks of soap....

Bob