Here is a puzzle.. I have been reloading for .223/5.56 since the late 80's.. the rounds reloaded have been used in different weapons from a Mini-14 to several makes and models of the AR-15 and M-16 platforms.. I have never had a reload round stick in the chamber before it is fired.. I have had to use a nylon hammer to get the charging handle to pull the round out.. I used a cage gauge to check and recheck the rounds and a mic to check and recheck the spec from atleast three different manuals.. the rounds are of different head stamps and using the 55 gr bullet.. The weapon is a S&W MP-15 and I have completly cleaned it.. it has nothing to do with the gas system because it is not fired rounds.. this is a live round right off the press.. also just for the guys that what to call this cazy to cycle rounds.. I have a firing pin for AR's that has been ground down so it does not hit the primmer since the AR is a floating fifing pin.. that should keep folks on track.. any good ideas as to why this is happening and how to fix it.. it is only the MP-15 so it is weapon specific.. I have thought about using a lapping compound and polishing the chamber.. What do you think?