Broke another bolt.... your thoughts??

[Cajuntransplant]

Did you lap the receiver face to ensure the barrel is square with the upper receiver? It has been speculated not being square can contribute to early bolt failure. More Velocity usually equates to more pressure, AR Comp hasn’t been used as much as other powders.

Another forum member broke a couple bolts running IMR8208XBR with 107 grain SMK. His loads exhibited the same trait as yours so it is possible with the chamber heat plus suppressor your adding additional pressure/bolt thrust. Curiours where your spent brass is landing. If the brass is landing at 1-2 O Clock it sounds like you could still be over gassed.

I’ve never used any rifle length gas 18” barrels and I don’t know if this gas system plays well with suppressors. Others on the forum have more experience than I do with suppressors and maybe they’ll chime in.

No never did any lapping of any of my builds.... could be a hiccup with it I suppose but i've had this rifle a few years now I think and this has only started happening since I started running suppressed. But first bolt broke after a couple thousand rounds. This one after about 500-600 I think. I tried 8208 and didn't get the same consistency as ARComp and got a lot more pressure and didn't get same velocities without bad pressure signs.

All the brass lands at 330-4 oclock consistently.