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Posted: 2/5/2005 6:57:39 PM EDT
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I spent an hour at the range on friday zeroing-in an optic at 150 feet. I was shooting in the prone, using a bi-pod. Let's assume the optic and mounts are working fine. It's a 20" Bushmaster 1/7 twist (custom) with phantom flash hider and I am shooting the XM193-PD (from ammoman). The barrel has fewer than 500 round through it. I finally get to the point where my groups are all hitting within a half inch to 1" circle, but every 4th shot or so I'll get a hit that impacts 1" outside the standard group. Later I switch to 62gr green-tip IMI. Sure enough these impact all in the same place... very consistent groups. Something else that was odd was that when I switched zoom on my optic from 16X to 9X the point of impact of the Xm193 changed (landing lower) but the IMI stayed the same the same! I didn't think that the 1/7 twist would make all that of difference versus the 1/9 twist with respect to the M193. And, out of my 14.5 inch M4 1/9 twist, this very same XM193 PD shoots fine (no wild hits). I guess, my question is that if I should expect XM193 to not behave out of the my 20", should I just switch to M855? I really don't want to be storing up two different types of 5.56, also Idon't want to give up fragmentation out of my 14.5". I guess the alternative is to just move up to heavier loads, 68gr and up, but doing so would be more costly, wouldn't it? |
| Everybody throws a flier from time to time, nothing to worry about. You are very lucky if your 55 gr bullets and 62 gr bullets impact in the same place, they usually don't. A change in the point of impact when changing power on a variable scope is quite common, everybody wishes it wouldn't happen...but it does. |
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That's one answer, yes. Remember, though: the "PD" ammo you're shooting is "Grade 3" ammo for a reason, and that inconsistancy is one of them. If you were shooting real military issue M193 (Grade 1), you would not be having those fliers, or very rarely. If you were shooting XM193 (Grade 2), you would still rarely have them. The "PD" loads say "For Practice Use Only - Not For Duty Use" for a REASON. -Troy |
Roger that... noted. My next batch of XM193 will not be the PD stuff. I bought this batch because that was all that was available at the time. Even still, for sub-grade ammo, I am still impressed that approximately only 1 out of every 4 or 5 are inconsistent... but then again, the price of the PD was not any better than the regular XM193 so perhaps I should be a little grumpy at least... |
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