In my Glock I pop out the barrel and drop a round in there, all is good. When I drop a round in the AR it drops right in and falls out with gravity. I just am not sure if the round is too long or not. In the asssembled gun I guess my question is that I do not know how to tell if the AR bolt is locked or not. On a bolt gun the bolt is down it is ready, but on the auto how can I be sure? Will it fire if it is not completely locked up? I just got a case gage (Lyman) and it will not accept many of my cases backwards that I have been shooting fine and suspect the gage, but I would like to use the actual chamber for a gage.