Posted: 11/2/2015 8:28:56 AM EDT
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I've been assembling AR15 style rifles for several years now. I've built a couple precision AR's in 5.56 using quality parts, achieving sub-moa accuracy. My latest build is giving me fits. I've tried 2 different precision barrels and am getting about the same results, around 2 moa with 2-3 shots in a small cluster, then 1-2 shots straying 2 inches or so.
I've checked about everything I can check but can't seem to locate the problem (scope mount, screws etc., different loads, ammo). I'm convinced its not any of the usual suspects. One thing I haven't checked is the upper receiver. I think this one is a Rock River. What could I look for in inspecting the upper? Can a bad upper cause accuracy problems? Any help would be greatly appreciated. |
| I am new to precision rifles, but the things I know of to look for in the upper receiver are the barrels head spacing, free floated hand guards, your barrels crown, if the barrel is properly mounted to the receiver, and your chambers dimensions. Again I am new, but mechanically all of these things could affect how the rifles accuracy is. |
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The accuracy is almost invariably traced to the bolt properly locking the cartridge into a chamber with correct headspace and a completely free floated barrel.
Other possibilities: Not broken in:: get at least 100 rounds through the action without FTFs. Something is damaging the ammo on its way into the chamber. {Hand cycling sharpied marked cartridges will find these.} The sights are moving around under recoil. {Dial indicator and vise} The Scope or mount has a major problem. {Try another?} |
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Quoted:
The accuracy is almost invariably traced to the bolt properly locking the cartridge into a chamber with correct headspace and a completely free floated barrel. Other possibilities: Not broken in:: get at least 100 rounds through the action without FTFs. Something is damaging the ammo on its way into the chamber. {Hand cycling sharpied marked cartridges will find these.} The sights are moving around under recoil. {Dial indicator and vise} The Scope or mount has a major problem. {Try another?} Can't really test that on an AR. The jacket is usually scratched when ejected. |