Author Topic: Terminal Ballistics in Clay  (Read 143 times)

Bullfrog

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Terminal Ballistics in Clay
« on: January 09, 2019, 08:08:24 PM »


Over the past month I've done a lot of shooting into clay at 50 yards with nearly all of my airguns. I've found that the clay is much easier to work with than ballistics gel as it can be infinitely reused, subject only to having the wound channels be pounded in between shots.

The above picture shows what happens with bullets over expand at high velocity. The bullets on the top are .308 NOE cast 98 grain hp, the bullets on the bottom are .45 NOE cast 218 grain hp Bob's Boattails. The lead allow is random tire weight lead that's been heavily slagged. The left bullets that only have a base left represent muzzle velocities of 940-950fps in the .308 and 900fps in the .45. The bullets on the right represent muzzle velocities of 810fps and 755fps respectively in the .308 and 830fps in the .45. Impact distance on all shots is 50 yards.

I've very encouraged to see my alloy perform so well at lower velocities. Over the past year that I've been casting, I thought my allow was hard and brittle. In fact, I've simply been firing the projectiles too fast for optimal mushrooming. Although in truth there isn't a major difference in the wound channels between the fast bullets that fragment and the slower bullets that mushroom. Both offer almost the same size wound and depth of penetration.


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Alan

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Re: Terminal Ballistics in Clay
« Reply #1 on: January 10, 2019, 04:49:43 AM »
A man after my heart! Since we are all here to learn, I have a few comments.

To correct one comment... 22LR bullets are not copper jacketed; they're copper plated to retard oxidation as are those which are wax coated for the same reason. Some .22 magnums, and certainly Winchester's .22 super mag use jacketed bullets.

Any projectile which doesn't exit the medium, no matter what that medium is, dissipates ALL of its energy within that medium. In the case of the .22LR, at 25 yards, about 150 FPE was dissipated. An average .30 caliber airgun has about 75 FPE at the muzzle, and a powerful one, about 100 FPE. I don't know what yours FPE was. But, since it completely cleared the block, less of its (total) energy was dissipated. I venture to say, it was less than half that of the .22LR.

I have had an interest in terminal ballistics for a very long time. If I have learned anything, it is that terminal ballistics are NOT an exacting science. It has always been thought that slow moving, large projectiles do more damage than small, fast ones. After all, your tests sort of prove that if we base our findings on the size of the (so-called) wound channel. However, if you would have shot that block using a .17 HMR (≈250 FPE), you would have blown it to bits! And yes, the bullet would exit the block!

The point I'm trying to make here, is although slow and large projectiles do a lot of damage to clay blocks. So will a lowly .22LR, and certainly a .17 HMR! But those facts alone, do not account for game in the pot. In fact, the vitality of the game in question, is just as important, if not more so!

I'm sure we've both shot game that got away, no matter what we used to shoot them. And then we ask ourselves, what the heck just happened? Yet, we both have hit game in a poor spot, only to have it drop as if hit by lightning! And we still say... What the heck?

« Last Edit: January 10, 2019, 05:20:15 AM by Alan »
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