Ordered a couple of Chip McCormick Shooting Star magazines for less reloading at the range. They wouldn't feed correctly after putting them in the Defender for the first time. I tried several times to rack full magazines through using both FMJ and JHP ammo. Then I switched the springs from both McCormicks and both factory Colt magazines and the feed problems pretty much stopped, but now the slide won't lock back after the last round is ejected. Should I return the springs to their original magazines and take them to the range to see if the feed problems work themselves out? Or leave them like they are and work on the slide issue? Or, should I send the Stars back and get something else?