M&P 45 Slide Locking Back on Full Mag

[Oldstate]

I just got a new M&P 45 (my first M&P) and have 7 ten round mags for it. I have cycled them all equally through the gun in the first 270 rounds.

On 4 occasions with 2 particular mags the slide has locked back with rounds left. Is this the mags or is it just a coincidence and the gun is to blame?

All my searches have brought up issues with slides NOT locking back on the last round.

Other than this issue the gun is working fine will factory and reloaded ammo, both hardball and lead.

[nwhpfan]

I just got a new M&P 45 (my first M&P) and have 7 ten round mags for it. I have cycled them all equally through the gun in the first 270 rounds.

On 4 occasions with 2 particular mags the slide has locked back with rounds left. Is this the mags or is it just a coincidence and the gun is to blame?

All my searches have brought up issues with slides NOT locking back on the last round.

Other than this issue the gun is working fine will factory and reloaded ammo, both hardball and lead.

My first suggestion is to verify your grip is not the cause. It is possible to apply upward pressure to the slide lock and cause a premature lock-back; with your thumb, meaty portion of your trigger finger, etc. There is very little else that could cause such a phenomenon.

[Oldstate]

My first suggestion is to verify your grip is not the cause. It is possible to apply upward pressure to the slide lock and cause a premature lock-back; with your thumb, meaty portion of your trigger finger, etc. There is very little else that could cause such a phenomenon.

I'll pay closer attention to that but I'd be surprised if I were interfering with the slide. I called SW and they said to send the mags in for replacement.

[Al T.]

While your incidence rate is probably too low for this to matter, I've found that shooting with the opposite hand can diagnose grip issues (or lack there of) with the dominant hand.

[Oldstate]

While your incidence rate is probably too low for this to matter, I've found that shooting with the opposite hand can diagnose grip issues (or lack there of) with the dominant hand.

The gun has a saftey and I ride the safety with the same grip I use for my 1911. I grip high with my support hand both thumbs pointing forward. My support thumb is out and does not touch the slide.

That being said, I ran both mags a few times today and didn't have the issue. I'm probably still going to send them back to be sure.

I'm very new to the gun and I'm still getting used to the feel of the slide locking back so it takes me an extra second to realize something is wrong. It's not as pronounced as a 1911.

[Street Survival]

Hey Old State,

Larry Vicker's gets credit for this tip. Try shooting the weapon with your opposite hand and see if you still get the malfunction. If not, it's you. You will have to adjust your grip. Hope this helps, Good Luck.

[nwhpfan]

It's probably your grip. There is a little shelf on the magazine follower that engages the slide stop to lock the slide back when empty. With rounds in a magazine there is zero chance it can engage to lock the slide back. What is more likely is you are somehow touching one of slide release levers and pushing it up. Before you waste anymore time..just shoot it more and see what happens.

[DocGKR]

As noted above, put 50 rounds through each of the problem magazines using weak hand only--if there are no malfunctions, it is not the pistol or mags...