Originally Posted by
sinlessorrow
Pretty much, to mch pressure at the chamber to press the bolt against it.
That said I was reading BB's posts on a different website and they were talking about maint. And one big thing was how on M4's bolts should be replaced every 4,000 but can go 10,000. Barrels should be replaced every 12,000.
They also mentioned how pistons greatly increase bolt life, thats what had me wondering, WHY do pistons greatly increase bolt life from 4,000-10,000 to 20,000?(on the HK and LWRCI guns)