21 inch Criterion barrel chambered by Precision Firearms, Aero receiver, bolt group, and adjustable gas block. Tried 105 gn and 90 gn bullets. AC 2560, and LeverEvolution powders workups. Gas block is now at full open and has been removed and checked a few times. I am using ASC 5 and 10 round magazines and also a 6.5 Bobsled single feed. The bolt has locked back maybe 3 times out of 300 or so rounds, Cases eject from 4 o'clock to 3 o'clock depending on powder load and gas block setting. Magazines and lower work fine on two separate rifle length 6.5 Grendel uppers and a rifle length .223. I also tried 2 other bolts from my Grendels and waxed the bolt contact areas in the upper. The bolt drops in easily and does not seem to be hanging on the gas tube. I am running out of ideas here and about ready to either enlarge the gas port (last resort), try a non adjustable gas block, get another lower and with a lighter buffer spring or pull the barrel and gas tube and install on another upper.
All suggestions welcome and thanks in advance
Jim
Oh and as a side note I ran into a buddy at the range who is having the same problem with his 6 ARC build. I have no idea what his build is but he is also a experienced AR builder. Is this a common problem with this cartridge?
All suggestions welcome and thanks in advance
Jim
Oh and as a side note I ran into a buddy at the range who is having the same problem with his 6 ARC build. I have no idea what his build is but he is also a experienced AR builder. Is this a common problem with this cartridge?