Shot my brand-new AR10A4 today to sight in the scope. First 5 rounds went downrange without a problem, then every round after was FTE. Empty case gets halfway out but doesn't eject fully, new round gets stripped to load by B/C but can't 'cause the old casing is still in the chamber.
Sooooo, went to Armalite and checked "Technical Bulletins", found no issues which would cause my particular problem. My bolt is not from "C" lot, extractor has the little rubber "O" ring. I used NATO ball surplus to get on paper (Lake City '83 mfg), then factory Federal for the rest. Went home and cleaned everything up, somewhat dejected, but happy that the bastard grouped like a mo'fo'.
Any ideas??? Is this thing just ammo-finicky?