Saturday, November 15, 2008

Airgun Pellet Testing in Ballistic Gel

Ballistics Gel Testing of Different Pellet Types and Calibers

I decided to conduct some tests using ballistics gel to simulate animal tissue. For the tests I Used 2 different air rifles in 2 different calibers. I used a Benjamin Discovery .22 caliber pellet gun, and a Ruger Air Hawk .177 caliber pellet gun. The ballistics gel was made according to FBI specs and calibrated to their standards to get the formulation down right first. To simulate animal hide, I placed a piece of leather from a welding glove over the front of the gel block. While this is much tougher than the hide on most small game, I thought it would be a good test to weather these pellets could penetrate a heavy hide, and still have enough velocity and energy remaining to cause expansion and a sizeable wound channel. In tests done by the engineers over at Federal Premium Ammunition, the addition of a deer hide made a small difference, causing the lighter bullets to come apart a little more. That test was done with a 30-06 rifle and although it made some difference, I expect the addition of the hide will make a much bigger difference for the relatively low velocity and small caliber I would be shooting with. The results were surprising to say the least with the addition of the hide reducing penetration by about 25% and the final expansion of the pellets was less than the bare gelatin testing previously done. For a comparison, a 36 grain hollow point fired from a 22lr, penetrated 11 inches. For the .22 caliber tests I selected 4 different pellets. My goal in this test was to see which pellet expanded the most without fragmenting, and gave the shortest wound channel. Thus indicating the best energy transfer. The Shots were taken from 5 feet away to eliminate muzzle blast as a factor. While you rarely shoot an animal point blank, the test will give you an idea how each pellet performed and if expansion didn't occur at these high velocities, chances are, as the velocities dropped, the results would be even less spectacular. Unfortunately I only got a few good clear images of the Gel as my camera is just a cheap camera phone and the glare from the light blocked the wound channels from view on most of the shots. The few shown were the Discovery PCP hollow points .22, the Gamo Magnum .177, and the RWS Superdome .177. There are however pictures of all the unfired pellets and the recovered pellets after firing. First up will be the JSB Predator pellet in .22 caliber. Velocity was 800 fps. The pellet penetrated a total of 6 inches and left a very explosive wound channel up front. The plastic tip came off within the first inch of penetration, which indicates the expansion is definitely occurring up front. A good sign for sure and the pellet didn't fragment at all and held together to make the widest wound channel possible for as long as possible. The wound channel it left behind was the largest of all the pellets tested. The final head diameter was much larger than the unfired pellet with a final diameter of about .28 inches.

JSB Predator shown new and after it’s trip through the hide and 6 inches of ballistics gel

Next in line was the RWS Super-H hollow point pellet. Impact velocity was 860 fps. The pellet's point expanded within the first inch and was nearly as explosive as the Predator's as indicated in the gel block's permanent cavity. However, the point then rolled back and flattened out against the skirt leaving a final diameter not much more if any bigger than the unfired pellet's diameter. Surprisingly, the head did not separate from the skirt but it seems it came pretty close. The resulting wound channel after the first inch was much smaller than the Predator's and it penetrated a total of 7.5 inches indicating it didn't transfer it's energy as good as the Predator did. I suspect optimal expansion with this pellet will occur at a lower velocity.
In the future I will do a 25 meter tests with all the pellets mentioned in this review to confirm this.

RWS Super-H point shown new and after passing through the hide and 7.5 inches of ballistics gel

Next was the Discovery PCP hollow point pellets. Impact velocity was 840 fps. This pellet expanded slightly with it's expansion characteristics more similar to a heavy domed pellet than a hollow point. The expansion came from the rear of the pellet flattening out against the head, reducing it's length, and spreading the head slightly. The hollow point cavity had very little deformation to it. The head was flattened out slightly probably due to initial contact with the hide. Final diameter was about .23 inches. Total penetration through the hide and gel block was 8 3/4 inches. This pellet I think would be more suitable for larger game such as raccoon, or perhaps fox if your gun is powerful enough.

Benjamin Discovery pellet after passing through the hide and 8 3/4 inches of ballistics gel

For the next test we jump to a different caliber. We go to the Ruger Air Hawk .177. The first pellet was the Crosman Destroyer. I know from previous testing that this pellet expands much more than standard domed pellets and some other hollow point style pellets. So if anything was going to do it, those would. These pellets have a hollow head with a small point in the middle. I suspect this helps with the expansion by forcing liquid from animal tissue down into the head and spreading it open. Impact velocity was about 850 fps. I must say I was quite impressed. The pellet's wound channel was almost as big as the larger .22 caliber pellets. The expansion started within the first inch as indicated by the permanent cavity left in the gel block. As the pellet continued to travel, it left a sizeable wound channel and the head continued to expand while it traveled until after roughly 5 1/2 inches of penetration the head peeled off. After the head peeled off, what was left of the pellet, formed a very distinct very pointy cone, and continued to penetrate another half an inch for a total penetration of about 6 inches. The point in the hollow head and the skirt seem to stay together in all subsequent tests. The result is a very distinct, very pointed cone. While I normally consider this type of pellet head/skirt fragmentation a bad thing, because the little skirt has too little mass and can deflect off of bone and miss the vitals, because the fragmentation occurred so late in the wound channel, at roughly 5 1/2 inches, on small game that wouldn't matter at that stage because the pellet would have long been expanded and have reached the vitals before fragmentation occurred. Because of this, I am definitely going to have to give this pellet a definite thumbs up for it's destructiveness in this medium.

Crosman Destroyer shown new and after it’s trip through the hide and ballistics gel

The Next pellet was the Gamo Magnum. This pellet did a lot better than I had expected. Velocity was about 830 fps. The pellet flattened out a lot more than I had expected it to. Probably because the entire pellet is hollow, not just the skirt. Total penetration was 5 3/4 inches. A lot less than expected. This is definitely a good thing. So far this pellet penetrated the least out of the .177 caliber pellet. A .177 pointed pellet penetrating the least? That was surprising to say the least. The next pellet in line was the RWS Superdome in .177. Velocity was about 850 fps. The pellet's skirt flattened out against the skirt and like the Gamo Magnum, expanded more than expected and penetrated less than expected. The Superdome Penetrated a total of 6 1/4 inches. Although it penetrated the most out of all the .177 caliber pellets tested, it still was a lot less than expected with the penetration barely longer than the Crosman Destroyer. However the wound channel was considerably smaller.

RWS Superdome pellet on top and Gamo Magnum on the bottom after their trip through the hide and ballistics gel. The wound channel on top is the latter half of the wound channel left by the .22 cal Crosman Discovery Pellet. Gel block was cut in half for easier handling and better light transmission.

This is only the first part of the report. The second part will record the results from the same pellets, and the same rifles, from 25 yards away to give a look at the downrange performance.
I made quite the discovery today. It seems the addidion of the hide does 2 different things for different pellet types. With pellets designed not to expand like heavy round nose pellets like the Beeman Kodiak .22, and other round nose pellets, it reduced the penetration as expected. (Beeman Kodiak is the leader in penetration so far, completely penetrating the 12 inch gel block from my Benjamin Discovery. Velocity was 715 fps. I would definately recomend this pellet for larger game like raccoons, fox, and other tough animals. With the pellets designed to expand however, the hide did just the opposite! It actually slowed the pellet down enough to decrease the expansion while the pellet still maintained enough velocity to penetrate the gel block. The Beeman Crow Magnum .22, penetrated 7 inches with the hide and showed some expansion but not as much as the Predator .22. Without the hide, it penetrated only 5 inches, muchrooming into a perfect little mushroom with a diameter of almost .40 inches.


Mark said...

Very thourough and informative...thank you for the information. Appreciate it very much. Your report seems very objective.

Blind Dog said...

Very nice and thorough report. I have found the same phenomenon with shooting at soft clay, both covered and uncovered, with expanding type pellets--that the covering (pigskin or denim, etc.) will tend to reduce expansion and thereby increase penetration.

Will we ever see part 2?


Sebastian Jones said...

cool blog dude. would be better w/ higher quality pictures.

Monih said...

And how about the nibs - rumored to be powerful and dangerous available almost everywhere