Aa upper quality question

[noone]

I had problems with broken bolts until I learned that the face of the upper receiver has to be square with the bolt to insure even pressure on the barrel nut. Since I got the Alexander Arms upper, and had the upper receiver lapped to square on my other rifle, I haven't had any issues. My guess is that the Alexander Arms uppers are either lapped to square, or the tolerances are just more demanding than "mil-spec". Only Mr. Alexander could say for sure.

All I know is that with the Alexander Arms upper, I haven't had any problems or broken bolts...