Gun is awesome- carries easy and is very accurate. Today I put 150 rounds through it- mixed HP and FMJ. All 230 grain. No problems loading, firing, ejecting. Zero FTF, FTE, etc. So the problem: The slide doesn't lock back on an empty magazine. I used four different magazines. Same result. The same problem occurred last range trip. If I put an empty magazine in the gun, then manually rack the slide, it engages the slide lock. Ideas?