Barrel installation problem. Whats going on here?

[Tactical30]

I have put together about 7-8 AR-15's in the past. The most recent AR/.223 build I had a problem while installing the barrel.
After I had finished putting everything together, the bolt did not line up with the bbl ext correctly. It seemed like it was off just enough to hold the bolt up from closing. I have never had this problem before.

I loosened everything up and it seemed to go in perfect but as soon as you tighten the barrel nut up it turns very little, like I said just enough to hold it up.(counterclockwise if you were looking at it thru the upper reciever.)

What the hell is causing this to happen?

-The barrel is a brand new.223 Wylde Chamber/ 18" WOA w/ Stag arms M4 ramp ext/Mid gas
-Bran new BCM Upper reciever
-Larue 13.2" Handgaurd

 

[DWALKER]

Re: Barrel installation problem. Whats going on here?

There are a couple of possibilities. The index pin the barrel extension could be loose and allowing the barrel to turn slightly when you are tightening the barrel nut. The slot in the receiver could also be oversized or worn. Other than that, it is possible that the barrel extension or the bolt is out of spec but not likely.

 

[Hummer]

Re: Barrel installation problem. Whats going on here?

I have a friend who was a procurement contractng officer with the gov't for the M16 parts and had a conversation with him about two months back. He says 95% of the parts on the market do not meet the gov't drawings for M16 so tolerances may be gone to hell in a hand basket. You don't really know what you are buying he tells me. He also tells me there are a couple guys in Iowa making outstanding bolts and will be in production soon for ARs. Sorry I don't know the name but he says their quality is excellent.