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Posted: 1/5/2009 7:41:27 AM EDT
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I put a 3-9x scope on my flat top 16" Stag for coyote hunting. I sighted the scope in using Winchester 5.56mm white box ammunition (55gr FMJ). On the day I sighted in, I had a partial box of 223 Remington UMC I needed to shoot, also 55gr FMJ. However, the UMC had an impact point about 4 inches below where I was sighted in for the Winchester.
Now, I expect my Mini-14 to be picky about it's ammo, that's a known trait of that rifle. I didn't expect the Stag to be that finicky. Is this normal? Could it be due to the difference between 5.56 ball and commercial 223? Another thing I remembered. I had my AR in a shooting vise to sight in when I was shooting the Winchester 5.56. My vise sits kind of low, and I couldn't get the gun in the vise with the 30rd magazine in it. So I loaded them one at a time and shot the Winchester without the magazine in the rifle. When I shot the UMC, I shot from a regular rest with the magazine attached. I didn't think this would make a difference, but I suppose it's possible. Anyone have any experience with that? |
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I always assumed the factory loads were as hot as they could safely make them, therefore any factory 55gr FMJ load should be roughly the same. Apparently I'm wrong about that.
Oh well. Time to spring for 62gr hollow points and sight in again, since that's what I'm planning on using on the yotes. |
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Quoted:
I always assumed the factory loads were as hot as they could safely make them, therefore any factory 55gr FMJ load should be roughly the same. Apparently I'm wrong about that. Oh well. Time to spring for 62gr hollow points and sight in again, since that's what I'm planning on using on the yotes. M193 = M193 if it aint M193 specs it aint M193 223rem is different than 5.56mm M193 just a tad hotter by 100 to 200 FPS Alot of guys think a 223rem 55gr fmj = M193 Remember 12GA  not to bust ya ball
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When the bullet starts moving, so does the rifle. Sighting in with the rifle clamped in a vise WILL have a different impact when shot normally. All is fine.
Those of us who shoot in various positions have noted a slight change in impact depending on position. For example, shooting in the standing has the least resistance to the recoil while prone provides the greatest resistance to the movement of the rifle. |
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I always knew that recoil was felt more shooting prone or from a rest (I learned this the hard way as a teenager shooting an 8mm mauser) but it didn't occur to me that it might affect POI. Makes sense though.
The vise altering POI is kind of a bummer. It's not AR related, but I hunt with a Rem 710 in 7mm remington magnum. I got a Nikon Prostaff scope for it for Christmas, which is a fine quality optic. It's got a bullet drop compensator in it, and for magnum calibers you're supposed to get best results sighting in at 200 yards. There was a time, when I was a teenager, that I could zap beer cans at 350 yards with a 20" AR-15. Now, I have trouble holding steady on a target at 200 yards even off a rest to sight a gun in  So depressing...
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