will not load a new round off of the magazine. This is with different Armalite magazines and with the standard buffer and a Slash 10 oz buffer.   Ejection is normal.   The rifle has approx 175 rounds fired thru it   The chamber and the feed ramps required polishing.   The only other thing was the gas block was sitting on the barrel shoulder and there were no shims or spacers installed.   Any ideas?   Thanks