I haven't been able to get to the range lately. However, I'm going to try some factory 208g cartridges. I did notice today that it is very dry, the bolt, bolt carrier, etc. So:
I'm going to lub it more before I shoot.
I'm going to change bolts and bolt carriers with my .223 rifle to see what happens.
I'm going to put a 223 upper on the lower to see if the recoil spring works ok.
That should narrow it down without spending any more money other than cartridges.
I've rebuilt it twice and can't see anything wrong. Like I said, never had this problem with 223 uppers.
I did see where H-110 and 296 max loads in Lyman book is 17.8. (I used 17.5). The Hodgdon online said use 17.5 of H-110 with a carbine length barrel.
It is a heavy barrel. I do remember measuring the diameter of the gas hole in the barrel and it was bigger than minimum recommended. It was fairly large, so that isn't the problem.
Would the gas block have to be specific to 300 BO or is the standard block ok? If the gas tubes are the same what would that matter? From everything I have read, only a barrel change is necessary from 223/556 to 300 BO.
