M&P slide lock issues

[Phillygunguy]

Hey folks, So I love the M&P so much I got another this time its a pro series in 9mm 4.25 bbl. So far I put 450 rds though her 350 today alone mostly Remington umc ball 115 gr. and about 100 being federal hst
around the 250 mark I noticed the slide not locking back after last round fired. I tried multiple magazines and all the same results also when racking the slide I noticed it got a little gritty chambering a round wasn't as smooth . I had cleaned the gun prior to shooting it for the first time then cleaned after putting the first 100 through it .So my question is Is this because its just dirty? or something I should be concerned about? Oh I had no other issues such as FTF etc it ate everything i fed it.

[backspur]

Post edited for stupidity.

[Phillygunguy]

I thought auto forwarding was when you insert a loaded magazine at a certain angle and amount of thrust while the slide is open it slams the slide closed and chambers a round, My issue is after firing a magazine the slide doesn't lock back

[backspur]

Yes, that is correct. I obviously didn't thoroughly read your question.

[Aggie510]

Sometimes this happens to me while shooting my Glock. I've noticed it is caused by my thumbs forward grip. The thumb of my off-hand (left hand in my case) rests on the slide release causing it to stay down after the last shot in a mag. The spring force of a magazine isn't very great so it doesn't take much pressure to keep it down.

Pop some empty mags into the gun and rack the slide, if it still doesn't lock back I might recommend a couple of things.

1) Check the integrity of the magazine that the lock back failed on. If it needs be, mark the mag and keep it out of your gun for carry purposes.

2) Insure that the slack catch is free to move. Check for debris and drop a dab of oil on the catch's hinge.

If all else fails, send it back to S&W. They will be glad to fix the issue.

[Phillygunguy]

Thanks Aggie510 I actually just read that on the M&P forum about 5 minutes ago:p My thumb does make contact with the slide release so Ill try to keep it off next time I go to the range

[Phillygunguy]

Well back to the range today with 150 rds and not slide lock issues after keeping my thumb out of the way But I want to run it dirty some more to be sure