Penetration and Expansion Testing

[remtom1200]

I predict the mr hollowpoints will create enough pressure at higher fps to swell the soap block to the point it will break open.

[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

[remtom1200]

Possibly at lower velocity the skirt is not expanding enough to make a proper seal? It doenst look like very deep grooves, but I'm left wondering if the heavier band at the skirt area may be the culprit. Or I suppose the opposite could be true as well...too tight for the barrel and air is escaping at the weakest point which may be the bolt probe seal?

[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 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

[rsterne]

I recast the soap into some 5" x 9" x 3" loaf pans last night.... Putting the metal pans in the freezer for a half hour let the soap fall right out of the tapered pans.... I stacked the two blocks end to end, and this turned out perfect, as combined with the meplats on the .257 cal bullets, the penetration was not an issue, even at 130 FPE.... The solids penetrated completely through the first block and a couple of inches into the second, leaving the other end of that block for testing the hollowpoints.... Here is a photo....



From the left, the upper is the 87.2 gr. RCBS solid, the lower the 73.4 gr. Lyman solid.... both having already penetrated 9" of soap....
From the right, the upper is the 77.2 gr. RCBS hollowpoint, the lower the 66.0 gr. Lyman hollowpoint....

The solids flattened completely on the nose, and had less penetration at 130 FPE than the lighter round nose solid I tested yesterday at 85 FPE, even though the velocities were similar.... In addition, the entry hole was larger, and the heavier 87 gr. bullet, which had a larger meplat, created a larger entry (larger actually than the hollowpoints) and had slightly less penetration than did the lighter 73 gr. solid.... I think this clearly shows the effectiveness of a meplat in controlling overpenetration and creating a larger wound channel, even without siginficant expansion occurring.... Once again, the two hollowpoints blew apart, with the fragments only penetrating 1/2 to 2/3 the distance of the base, but creating a massive wound channel.... Here are the recovered bullets....



The top row is the Lyman "65 gr.", and the bottom row is the RCBS "85 gr." Cowboy....
On the left is an unfired solid, in the middle a recovered solid, and on the right a recovered hollowpoint....

The hollowpoints were cast using the largest pins that Erik supplied with his hollowpoint conversions.... If I used a smaller pin, the bullets would be less likely to come apart at these velocities.... The solids penetrated 265 mm (10.4") for the 73 gr. and 255 mm (10.0") for the 87 gr..... The hollowpoints were also nearly identical to each other, 110 mm for the 66 gr. and 113 mm for the 77 gr. (4.3-4.4").... At some point I will cast some hollowpoints using a smaller diameter and/or shorter pin.... and I plan to also test these different configurations at various velocities to simulate different ranges.... I'll likely wait until I determine what the downrange velocities are (ie the BC) so that I can simulate impacts at about 50 and 100 yards....

Bob

[remtom1200]

whooh those hp's blew!

[rsterne]

Minced Marmot.... *grin*....

Bob

[rsterne]

Here is a comparison I'm sure you've been waiting for -.22 Rimfire bulllets..... I initially used two 5" x 9" x 3" blocks of soap end to end, but the only one that required that was the .22LR Solid (140 FPE).... Here are the photos....



The photo above shows the track from the 40 gr. Long Rifle HV Solid at the top (straight through), with the other two being LR High Velocity Hollow Points (135 FPE).... I cut one wound channel open and tried to highlight the cavity with a marker, you can see the point where it mushroomed and caused the wound channel to expand....



The second photo show the captured LR High Velocity solid, about 2" into the block and turned sideways from the left.... From the right, top to bottom, are the .22 Short High Velocity 29 gr. Solid (75 FPE), the 27 gr. HV Short (73 FPE), and then a 29 gr. CB Cap ~ 710 fps (32 FPE), also spun around.... Below are the recovered bullets....



Top row, left to right: Short HV Hollowpoint, then the two Long Rifle HV Hollowpoints....
Bottom row, left to right: CB Cap, Short Solid, LR Solid....

All the High Velocity Hollow Points performed perfectly, although one of the Long Rifles shed the nose portion in fragments (one of which I lost).... The solids showed no expansion, although the Long Rifle was starting to flatten.... Now the big question, how did these compare to the Air Rifles?.... This requires looking at the .22 Short and Long Rifle Rimfires separately....

Compared the .22 Short High Velocity Rimfire, there are several notable comparisons in penetration....

.22 Short Rimfire 29 gr. Solid @ 75 FPE - 149 mm
.22 cal JSB Monster 25.3 gr. @ 37 FPE - 137 mm
.25 cal H&N Baracuda 30.9 gr. @ 50 FPE - 158 mm

.22 Short Rimfire 27 gr. Hollowpoint @ 73 FPE - 90 mm
.22 cal H&N Baracuda Hunter Extreme @ 37 FPE - 85 mm
.25 cal H&N Crow Magnum @ 50 FPE - 85 mm
.25 cal JSB Predator Polymag @ 50 FPE - 92 mm

Similar penetrations to .22 Short Rimfire amnumition are available with PCP airguns of power levels that are relatively common today, at very close range.... As expected, the .22 cal Airgun at 37 FPE outpenetrated the .22 CB Cap at 32 FPE, with all solid pellets.... However, the pellets used by these guns will see the power drop off relatively quickly with range, compared to a .22 Rimfire bullet.... Now let's look at the .22 Long Rifle, and more powerful .25 cal airguns shooting bullets not pellets and compare the penetration....

.22 LR Rimfire 40 gr. RN Solid @ 140 FPE - 277 mm (turned sideways)
.25 cal RCBS 53 gr. RN Solid @ 85 FPE - 318 mm
.25 cal Lyman 73 gr. FN Sollid @ 130 FPE - 265 mm (nose flattened)
.25 cal RCBS 87 gr. FN Solid @ 130 FPE - 255 mm (nose flattened)

.22 LR Rimfire 37 gr. Hollowpoint @ 135 FPE - 136 mm
.25 cal Mr. HollowPoint 50 gr. HP @ 85 FPE - 105 mm
.25 cal Lyman 66 gr. Hollowpoint @ 130 FPE - 110 mm
.25 cal RCBS 77 gr. Hollowpoint @ 130 FPE - 113 mm

Comparing solid bullets is relatively easy.... although the 50 gr. @ 85 FPE penetrated further relative to its power level.... Perhaps had the .22 LR Rimfire not spun around.... and if the heavier airgun bullets didn't have meplats and flattened.... we would have seen more consistent results.... However, when you consider they all penetrated over 10", does it really matter for the size game they would be used on?....

Looking at the hollowpoints, just based on penetration, the Rimfire bullet comes out on top, but it has a very tiny HP cavity, and stayed largely intact.... The airgun bullets, with their large HP cavities, all came apart quite explosively just after impact, creating a much larger wound channel than the rimfire bullet, just not as deep.... I would pretty much say call it a draw, FPE for FPE between the .257 cal airgun and the .22 LR rimfire.... Something else to consider is that the bullets will also carry just about as well.... so we're back to the "Dangerous Within One Mile" warning on the rimfire boxes.... A modern .25 cal airgun can indeed be the equivalent of a .22 rimfire....

Bob

[rsterne]

I finally got around to testing some .177 pellets.... With the .22 cal results being so predictable, basically if it doesn't expand, the heavier the pellet the deeper it penetrates for a given FPE level, I only tested the hollowpoints in .177.... I did test one JSB Exact Express 7.8 gr. Round Nosed pellet at several velocities, and it far outpenetrated all the hollowpoints at each power level tested.... I started at 12 FPE, went to 15 FPE, and then tested the two heaviest pellets at 18 FPE.... Here is the photo of those tests....



From the bottom, shot at 15 FPE, left to right:
RWS Super HollowPoint 7.1 gr.
H&N Terminator 7.1 gr.
Crosman Destroyer 8.0 gr.
Crosman Premier HP 8.0 gr.
JSB Predator Polymag 8.2 gr.
H&N Crow Magnum 8.8 gr.
H&N Baracuda Hunter 10.2 gr.
Benjamin Discovery HP 10.5 gr.

From the top, shot at 12 FPE, same order, but right to left....

At 18 FPE; from the left Benjamin Discovery HP 10.5 gr.; from the right H&N Baracuda Hunter 10.2 gr.

I then used another block, and tested the lighter hollowpoints at 7 FPE and 9 FPE, as follows:



From the bottom, shot at 9 FPE, left to right:

RWS Super HollowPoint 7.1 gr.
H&N Terminator 7.1 gr.
Crosman Destroyer 8.0 gr.
JSB Predator Polymag 8.2 gr.
H&N Crow Magnum 8.8 gr.
JSB Exact Express 7.8 gr. (for comparison)

From the top, shot at 7 FPE, same order, but right to left....

Here is a photo of the recovered pellets at 12 FPE (top row), 15 FPE (middle row) and 18 FPE (the two in the bottom row)....



Again, same order, left to right by columns:
RWS Super HollowPoint 7.1 gr. (nose peeled off)
H&N Terminator 7.1 gr. (nose peels off at 15 FPE)
Crosman Destroyer 8.0 gr. (nose peels off at 15 FPE)
Crosman Premier HP 8.0 gr. (starting to mushroom at 15 FPE)
JSB Predator Polymag 8.2 gr. (nose rolled back over body, tip left behind)
H&N Crow Magnum 8.8 gr. (nose peels off at 15 FPE)
H&N Baracuda Hunter 10.2 gr. (starting to mushroom at 15 FPE, more at 18 FPE)
Benjamin Discovery HP 10.5 gr. (just starting to shorten at 18 FPE)

Here is a photo of the pellets I tested at 7 FPE (top row) and 9 FPE (bottom row):



Again from left to right:
RWS Super HollowPoint 7.1 gr. (nose peels off at 9 FPE)
H&N Terminator 7.1 gr. (nicely mushroomed)
Crosman Destroyer 8.0 gr. (nose rolled over at 9 FPE)
JSB Predator Polymag 8.2 gr. (just starting to open at 7 FPE)
H&N Crow Magnum 8.8 gr. (nicely mushroomed)

Careful examination of how the expansion of these hollowpoints progresses as the FPE increases will allow you to pick one that performs well in your gun.... Don't forget that these are the IMPACT energies, not at the muzzle, so you have to allow for that.... All five of the pellets in the second set look like they will expand reliably at 7 to 12 FPE, although the RWS SuperHollowPoint sheds the nose portion at 9 FPE or over.... By the time you get to 15 FPE, most of the pellets that work well at low speeds are coming apart, with the nose portion peeling over the base and being left behind.... That's not all bad, as the base continues to penetrate, however.... At that energy, the Crosman Premier HollowPoint is finally starting to expand, as is the H&N Baracuda Hunter.... The Benjamin Discovery HP looks like it might start expanding at ~20 FPE impact energy .... but there aren't many guns that can launch it hard enough to have it arrive at over 900 fps, and I would question the accuracy if they did.... Don't expect it to expand....

Bob