This was happening on my AR this weekend. When I use 5.56 Brass it cycles just fine, not sure of .223 Brass I don't have any right now. But I bought some .223 steel case which is all I could find locally and the round would extract but it was catching the round out of the magazine, with what appeared a short stroke and jam. Not stripping cleanly. Just wondering if my chamber is a little tight for the steel rounds and needs more shooting done to losen it up ? Wonder if that is slowing down the bolt just a little.