We had this problem before. Thousands of chargers were made just a tiny bit out-of-spec, the lateral protrusions (the nubs that stick out on the sides, towards the chamber side of the charger were just a few thousandths too wide, this made it necessary to take them and just give them a light "tap" with a hammer. You could try it yourself, we did it to thousands of them with no problems. Lay the charger on it's side on a hard surface, preferably a vice, and then give the charging handle a firm tap with a hammer. This will compress the aluminum where the ears/stubs stick out, but BEWARE, if you tap it too hard it will squish the channel where the gas key rides and then it will drag in that area, so go lightly and test, tap and test. It has worked for us in the past. You can also look for evidence of this problem by examining the charger and looking in the upper receiver where the nubs ride. Good luck!