Posted: 6/21/2008 8:52:06 AM EDT
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AIM graciously sent me a small sample of ammo to evaluate, so this is this post will include some data that may be of use for you guys. This first report won't include any shooting data; I haven't had time to go to the range yet. Instead, I pulled 10 bullets, weighed the powder and bullets, measured the bullets and loaded ammo, and took some pics. The loaded ammo looks pretty much like any other Wolf ammo: Grey polymer coating, primer sealant, no neck sealant:  Pulling the bullets showed that they are definitely bi-metal, as they were strongly attracted by a magnet. I plan to shoot these into some water jugs to determine if they will fragment. As You can see, the bullet is not a true OTM round as the bottom of the bullet exposes the lead:  For comparison, the bullet on the left is a Hornady 75gr OTM bullet, T1 variant. The bullet looks a little weird because it was tarnished a little having been left in the garage for a few months. Here's the view of a sectioned bullet:  Nothing much to say - it reminds me of the 62gr Silver Bear I sectioned several years ago. Minimal cavity for the hollow point. That bullet did fragment, however, so we'll have to see if this one does as well. The powder is a short-cut extruded:  On to the data. Powder weight 21.1 21.1 21.3 21.3 21.0 21.0 21.1 21.1 21.3 21.2 HIGH: 21.3 LOW: 21.0 E.S.: 0.3 AVG: 21.15 StdDev: 0.12 I thought the powder charge is fairly consistent, pretty much what I would expect from factory ammo - maybe a little better even. The weight of the powder charge indicated a pretty fast burning powder. Based on the chronograph results I've seen so far would put this powder somewhere around Alliant Reloader 7, maybe even faster. This is speculation though. Bullet weight 74.0 74.7 74.3 74.0 73.5 74.2 73.7 73.2 73.9 73.8 HIGH: 74.7 LOW: 73.2 E.S.: 1.5 AVG: 73.93 StdDev: 0.42 The variance in bullet weight is definitely more than I expected. An extreme spread of 1.5gr. Bullet length 0.939 0.941 0.948 0.945 0.939 0.940 0.947 0.949 0.948 0.940 HIGH: 0.949 LOW: 0.939 E.S.: 0.010 AVG: 0.9436 I don't have one of those little tools that allow you to measure the length of the bullet from a specific spot on the ogive, so this is the overall length of the bullet only. The ES of 0.010" is very good, about the same as Hornady 75gr OTM. Loaded ammo length 2.238 2.233 2.240 2.241 2.240 2.247 2.241 2.238 2.240 2.244 HIGH: 2.247 LOW: 2.233 E.S.: 0.014 AVG: 2.2402 The average length of 2.240 will not present a problem for loading these into a standard AR mag. 2.260" is the max length for a .223 round to fit into a magazine. The ES of 0.014" is about on par with the variation on the length of the bullet itself, and I would say that seating depth is very uniform. That's about it for this first report; I might try to squeeze in a range session to chrono and shoot them into some water jugs. I will also section a bullet and post pics of that. |
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It's been a really long, hot summer, and I haven't felt like going out to the range. I finally had a chance to do some informal testing on this ammo using some water jugs to test fragmentation. I know there was one other person that shot the ammo into water-filled antifreeze jugs, and no fragmentation was noted. I'm not sure of the distance involved. I had 6 milk cartons to play with, and I thought 3 lined up would be enough; I was wrong. It turns out that the ammo did appear to fragment. The distance of the shot was 15 feet:  As you can see, the tip of the bullet is gone, and the lead core was pushed out. There were a few lead fragments left in the bottom of the milk jug. I *think* I found these in the second jug, but I'm not sure. The first jug had a near punctate entrance and exit hole, the third jug appeared to have been shredded somewhat - it would agree with the fragmentation I saw. Unfortunately, I should have used more jugs. Oh well. The second shot was pretty much like the first, although I found the lead core on this one:  Notice the jacket fragment stuck on the surface of the milk jug. Here is a closeup of the fragments of what I was able to find. The piece of jacket stuck in the plstic was the very tip of the bullet BTW:  All rounds fired just fine - there were no malfunctions. The ammo did fragment in this particular test, but I caution anyone to extrapolate too much from this test. Even though I saw the bullet fragment, I would expect the fragmentation distance to be fairly short. This is just my best guess; steel jackets are inherently tougher, and even a slight loss of velocity might mean that the bullet wouldn't fragment. If I collect a few more water jugs, I might try some longer distances. The second unknown is: when the bullet does fragment, how soon does it do so? If the yaw cycle starts too late, it may not be a good choice. Silver Bear 62gr JHP gave me the same results when I tested it years ago, but the same caveats apply. The only way to find out for sure would be to shoot some ballistic gelatin to eliminate the unknowns. But one thing is certain: In the words of O_P - shooting stuff is fun! |
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