Well I took my new (to me) Grade B to the range today. Shot great for the first 80 rounds or so. Great accuracy, nice recoil, nice trigger, everything I had hoped it would be. Then, on the last round of a magazine the slide stuck open about 1/2 inch. I cannot for the life of me pull the slide back. I can push it fully closed (with some force). The squeeze cocker appears to work just fine. Any ideas on what went wrong or how to fix it? I think this is a great firearm and want to use it as my CCW, but I must say I am now a bit worried. Hopefully this is an isolated problem. Thanks in Advance.