I have a 6944 and 9 magazines, 8 of which work fine. The only one that doesn't is a new (old stock) S&W factory LEO 12 rd. that I bought at a gunshow within the last year. It will not hold the slide open after last round.

Even though it appeared new, I ordered from the factory a new follower and new mag spring, and installed them. It still will not engage the slide release to lock the slide back when last round is fired.

What could possibily cause one factory mag with new follower and spring to not function when the other 8 mags do? The other 8 are a combo of factory, Meggar, and one no-name. Thanks for your help...

Top of the magazine deformed and not allowing the follower all of the way up?

Thanks '19, I had not considered that possibility, but it sounds very possible. I'll do a visual comparison. If that's it, I'm not sure how to fix it.

The original question must of been a tough one, since there is only one reply. Usually when it's a simple answer there is no shortage of folks letting you know. Thanks again!