Took the M9A1 out to the range today and I was a bit disappointed with the trip. I aquired her about a month ago brand new and she's right at 500 rounds now. I was shooting 115gr. CCI blazer for the first time, and I experienced some trouble. I shot 150 rounds and only once did the slide lock back after the last round. I also had the slide lock about halfway back halfway through a magazine with one live round in the chamber and what seemed to be another live round trying to feed. What would cause these two problems? Is there something happening with the gun, or is it just something I'm doing wrong (not standing behind her firm enough, etc.)? Thanks!