Accuracy of 20" Wilson Arms 6.5 Grendel Hbar Stainless Steel barrel

[LRRPF52]

So it looks like a .125 bolt is really designed for a 5.56 depth and the .136 is designed for the 7.62x39/220 Russian/Grendel based case. Why are they building.125 depth bolts? Since they are lighter seems like they would fail easier. I have always been a bolt gun guy and really liking the AR especially the Grendel.

Most of the companies making 7.62x39 never did the engineering work on how to make it work in the AR15, and ignored everything Colt did when it was a funded program.

Bolt face depth and extractor lip thickness are two of the main differences between a 5.56 bolt and a well-engineered 7.62x39 bolt, since the rim thickness is a lot more than 5.56/.223Rem.

When Bill A. was researching how to make a good bolt for the .50 Beowulf, he looked at the work on that project and how they solved a lot of the problems with getting a 7.62x39 to work in the AR15.

A deeper bolt face was one of the solutions to accommodate an extractor with sufficient lip thickness.

A .125" bolt face depth doesn't allow a lot of lip thickness for a rim like you find on x39 and Grendel, yet everyone in the industry makes x39 bolts and chambers set up for .125" face depth, and extractors fail left and right as a result. Their answer is to just replace them when they break.

If I had a .125" face depth chamber, I would personally use the LMT enhanced 7.62x39 bolt, but those extractors have broken on people too in full auto guns that are tortured. The bolts hold up better than anything out there in the x39 world because they're made from AerMet alloy, which is twice the cost of 8620 or 9310.