So I got a new Glock 19 gen 5. Every once in a while it won't chamber a round when I insert a mag with the slide locked back. This has happened two or three times. I have shot the gun a couple of hundred times and it has performed perfectly. I think the reason why it won't chamber a round is that I haven't inserted the mag in all the way or perhaps I am not pulling the slide hard enough back. When I am consciously inserting the mag with enough force I never have any problems and obviously pulling the slide back hard. So can you let me know if this is probably the case. I haven't had this problem with at glock 19 gen 3 and glock 26 gen 4. Perhaps a gen 5 is a little more sensitive.