obiwankabaldi

I found this in a discussion about bolts and compatibility. Also my BCG does not sit flush with the back of my upper assembly, sometimes making opening the upper difficult. It clears but it is definitely not flush. Cannot believe that the gun has functioned so well and suddenly developing issues....

I am confused and feel stupid since I never knew there were various configurations for a AR-10 bolt. I have a DPMS upper stamped 7.62 x 51 I have been shooting this rifle for a time with a BCG that I purchased online. Lately the bolt jams and the action will not open. Taking the bolt apart and checking Headspace I feel that it is way to tight. I did some research and found that there are 2 specs for bolts. One with a .125" counter bore to face of bolt and another with .129" counter bore to face of bolt. It seems that the .129" would be perfect. Where do I get such an animal if this is true. How do I know for sure which bolt I need?

I am confused and feel stupid since I never knew there were various configurations for a AR-10 bolt. I have a DPMS upper stamped 7.62 x 51 I have been shooting this rifle for a time with a BCG that I purchased online. Lately the bolt jams and the action will not open. Taking the bolt apart and checking Headspace I feel that it is way to tight. I did some research and found that there are 2 specs for bolts. One with a .125" counter bore to face of bolt and another with .129" counter bore to face of bolt. It seems that the .129" would be perfect. Where do I get such an animal if this is true. How do I know for sure which bolt I need?