I just bought a CZ-52, and I'm having problems with it. Every 2-3 rounds, the slide will lock back, and the round won't be stripped from the mag. The gun will eject (launch into the next county) spent brass just fine though. The slide just keeps locking back for some reason. When the slide locks back, it is usually stubborn about releasing, and it will take a pretty firm pull (probably more than should be required. Not sure since this is my first CZ-52) to get it to release. If you don't do it just right, the slide will just move back just a little, and then return to where it was (in the locked open position). Though, it did release easy once while I was shooting. It locked back like I explained above, but this time it slammed home when I just barely touched it. Any ideas?