I just picked up a CZ PO6. I have fired about 250 rounds through it so far. I am shooting 165gr and 180gr handloads with several different powders ranging from mid to max powder charge. It shoots good and has never missed a beat except that the slide does not stay back after the last round is fired. I have tried both of the factory supplied mags and the results are the same. Of all the rounds I have fired so far the slide has not stayed back once. Any ideas as to how to remedy this?