First thing I noticed, other then shooting about the same as my standard shield plus was, the front sight was noticeably misaligned. Next was the new 15 round mags don't lock back the slide on last shot. Apparently they sit a millimeter or so lower in the gun. They just barely catch the slide on the original shield. That said, 15 round mags are range only for it, unless S&W has a fix for this.