Greetings, TLDR: When the slide is locked back, every time, even if not fired, one of my mags will not drop freely and has to be stripped out (it will eventually drop if you shake it out). The other mag works just fine, every time. Both mags drop freely when empty with the slide in battery. What would cause this? 1st range trip for a used Gen 3 G23, which didn't appear to have been fired much if at all. Came with 2 10 round factory magazines that also appeared to be in like new condition. I shot 130 rounds of Winchester White Box 180gr using both mags. On the first full mag, the problem magazine(see above) didn't lock the slide back when empty. It locked the slide back properly when empty the next 10 times I tested it. The other mag worked flawlessly every time - locking back the slide and freely dropping when released. I'd like to keep the gun because it shoots great otherwise. I plan to go back to the broker and request a replacement mag. What else should I consider? Thanks.