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Posted: 3/22/2015 5:09:08 PM EDT
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The other day I helped my buddy put a free float Midwest industries rail on his bone stock bushmaster ar15. Everything went fine with the instal. A couple days later HE installs an end cap to the rail and a new flash hider on the barrel. Brings it over to show me and I noticed the barrel isn't centered? I don't know if it was like that after the initial rail instal or not but it shoots fine is accurate. Any ideas?
Thanks |
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I have the same thing going on with an A4,
I'm going to use the Brownells tool to lap (square up) the receiver face and see if that fixes it. http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/receiver-tools/ar-15-m16-upper-receiver-lapping-tool-prod20220.aspx |
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Quoted:
Don't lap the receiver unless it's absolutely necessary. Rail maybe a little crooked or the barrel is not perfectly round on it's outer diameter none of which is necessary a problem. If you are able to sight it in and it shoots fine I wouldn't worry about it. Nothing wrong at all with lapping the upper. I do it to every one that I build. It ensures the interface between the barrel extension and the upper is perfect, and this is exactly one of the problems that it fixes. A few thousandts difference in the face of the upper is magnified down the length of the barrel, so the longer the barrel the worse it is. The tool is easy to use, just don't go crazy with it. Once the anodizing has been touched all the way around the face of the upper you're done. If there was a deliterious effect on accuracy due to the face of the upper that will be corrected as well. There is a reason the benchrest guys ALWAYS to this. |
| If it shoots well, you don't have to mess with it. Not being perfectly centered isn't going to hurt anything. Between the barrel itself, the extension to receiver interface, the barrel nut, whatever system the handguard uses to attach to the rifle, the handguard itself, and the end cap, I would think there's very little chance for the barrel to be perfectly centered in the end cap anyway. By the time you take everything apart, mess with it, and put it back together, you might make it worse. If nothing else, ditch the end cap, then nobody will notice it anymore. |
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What MI rail is it?
This may, depending on how bad it is, effect your BUIS. You may not have enough adjustment to use them. Put a straight edge down the side of the rail and upper. Loosen the rail back up and retighten while gently nudging the end of the rail where you need it to be. |
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Quoted:
Don't lap the receiver unless it's absolutely necessary. Rail maybe a little crooked or the barrel is not perfectly round on it's outer diameter none of which is necessary a problem. If you are able to sight it in and it shoots fine I wouldn't worry about it. Lapping is certainly not an "unless absolutely necessary" drastic step. Trying to scare off the FNG's ? An off-center barrel/handguard will bother some people. Verify correct install of the rail. |
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