I have found that long protruding bullets are vulnerable to several kinds of accuracy issues. It is well know that gas gun chambering eats the tips on soft lead bullets and can cause concentricity imbalance. I have tested it with 6mm Creedmoors using LR308 frames. The result at 100 yards with an standard hunting SP bullet was 7+ MOA, BTHP less than 1 MOA. Well the same thing applies with 6mm ARC beyond bullet tip problems. The gas gun barrel extension can also be a cause of flyers in a good group. I have two 20" barrels, Faxon and CMMG. Faxon has standard untouched M4 barrel extension while the CMMG is modified. Feed ramp contact during chambering can screw up seating alignment just as easily as poor hand loading.
Attached images show ARs and barrel extension scaring. Anybody else found this kind of issue?
Attached images show ARs and barrel extension scaring. Anybody else found this kind of issue?