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I assembled the upper, but when I installed it on the lower, the end of the bolt contacts the buffer and would not allow the assembly to close. The bolt seems to lock into the barrel properly, but the end stocks out of the receiver 0.130". Do I need to shim the barrel? It is brand new as is the upper and bolt. Again, thanks for any advice.
That's a new one on me. Usually it's the buffer retaining pin allowing the buffer to protrude. Would have to guess that it's an out of spec upper. Esp. if the bolt assy. works with other uppers.
A shim seems not well advised. Another upper would be best, if that's where the drama lies.
Here's the whole story. I assembled this A1 using a new barrel with a F marked FSB - didn't know about tall FSBs. The rifle worked fine, but of course with the wrong/tall FSB, I couldn't adjust the elevation enough to get on target. Bought a new barrel from the same manufacturer with the correct FSM. Installed the barrel, but the bolt appears not to lock completely in the barrel. Could this be a defective barrel?
If it was working before then Q.E.D., I reckon.
How does it head space? The barrel extension sounds hokie to me.
Or the gas key. I had a gas key dot drilled deep enough, and once it was assembled, the gas key bottomed on the gas tube. Also had a friend that thought he got the roll pin through the right hole in the gas tube, but actually had the end of the gas tube bumping against it, so it stuck too far into the upper. It acted like the hole in the key was not deep enough. Try the build without the gas tube and see what happens.
One of those things, if I could just have it in my hands for a minute...we'd be shooting in five. It's usually something simple.