Brand New S&W M&P 9mm Pro Malfunctioning

[gregthehand]

Well I picked up my birthday/anniversary present last Saturday. It's a brand new S&W M&P 9mm Pro that my wife got me for our first anniversary and my birthday, which are four days apart. I bought it at Champion Firearms from Roger, which is where I buy 90% of my firearms by the way.

ANYhow I took it to our ranch on Saturday and put some Winchester White Box 9mm rounds through it and noticed that the slide wouldn't lock back on the last round. It locks back fine if I insert an empty magazine and then rack the slide however it wouldn't hold open after running round through it on an empty chamber. I took it to the WHIDPA weekly match last night and it shot like a champ and I was only two down for the entire match . However I was having the same problems with the slide going forward on an empty chamber and magazine. I'm using S&W normal capacity magazines however due to having to locate the pistol in a not so RKBA state it came with ten round magazines.

I know the obvious answer would be to send it off to S&W and have them make it run right. However I'd like to shoot it at this weekend's match and I really don't feel like going without her for a week or two. Are there any tips that someone can give me to possibly fix without having to send it off and get it worked on?

[stealthfightrf17]

Try switching to a diffrent ammo, aome people have been having problems with winchester lately.

[gregthehand]

I actually ran two boxes of Federal through it last night and I had the same problem.

[stealthfightrf17]

I would tend to say send it off then, you might be able to get them to talk you through what to do if you call S&W

[Middle Age Russ]

If possible, see how it functions with different magazines before sending the pistol back. Also number your magazines so that you can tell if it is a particular magazine issue. The mechanism to lock the slide back is pretty simple, but relies entirely on a particular ledge on the magazine follower pushing up on a tab to engage the slide lock. If the follower ledge does not consistently engage this tab you will have slide lock issues. There are only a limited number of items that can cause this. Here are some possibilities that come to mind.

Possible Gun issues:
Slide Lock tab is too small/bent/wrong shape to engage follower properly
Slide Lock is stiff (binding) and needs to be lubed/freed up.

Possible Magazine issues:
Weak Spring
Follower tilting (bad follower or magazine body)
Follower ledge too low/wrong shape or size to engage slide lock tab (bad follower)

Best of luck getting this sorted out. It is not fun to have equipment issues, even on a game gun. If it comes down to sending the pistol back to S&W, I am sure they'll take care of you.

[BrianSW99]

I had this problem on my Glock, until I figured out it was my grip. Without realizing it, my thumb was pressing against the slide release and causing it not to lock back. It happened most often during IDPA matches, which I figure is because when under the timer, I wasn't paying as much attention to my grip.

May not be your problem, but might be worth checking before sending it back to S&W.

Brian

[MoJo]

I had the same problem with my M&P 40 - - - there's nothing wrong with the pistol - - - it's YOU! I have rather large hands with long fingers I was riding the slide lock! Try the large grip and see if that cures the problem it did for me. Also you may have to train yourself to put your thumb into the memory groove below the slide lock.

[A-R]

I agree with possible reasons given - problem with mag/follower, mag release/spring, or end-user hitting mag release under recoil without realizing.

However, I'd also be concerned that all the anti-gun state law junk built into that gun (low-capacity mags, likely a mag disconnect safety, possibly an internal lock?) could possibly be causing a problem not often found on an M&P made for RKBA loving folks in Texas. Not knocking your gun at all, I'm just one of those who hates all the "safety" features that Kalifornia, Massachussetts, Illinois etc force into a gun not only for the anti-RKBA aspect, but also because I think re-engineering "features" into a gun mandated by ignorant politicians is a recipe for design flaws.

I've seen 10-round 1994-2004 Glock mags screw up the last-round lock back feature on a Glock and the same gun functioned perfectly with standard-capacity mags.

[mbw]

The Pro version of the M&P does not have the mag safety or key lock or thumb safety that some M&P's do.

Check your grip, that most likely is your problem. I have the same pistol and it has not missed a lick in over 2,000 rounds.

[mgood]

I had this problem on my Glock, until I figured out it was my grip. Without realizing it, my thumb was pressing against the slide release and causing it not to lock back.

That is very common. I can't guarantee that's what the problem is in this case, you (the OP) should look at how you grip the pistol and see if it's possible that you're thumb is putting pressure on the slide stop.

[A-R]

I had this problem on my Glock, until I figured out it was my grip. Without realizing it, my thumb was pressing against the slide release and causing it not to lock back.

That is very common. I can't guarantee that's what the problem is in this case, you (the OP) should look at how you grip the pistol and see if it's possible that you're thumb is putting pressure on the slide stop.

Good way to determine this is to fire a mag until empty using one hand and making certain your thumb is nowhere near the slide release. Typically the two-handed thumbs forward grip is what causes the strong-hand thumb to hit the slide release. with a one handed grip you should be able to ensure the thumb is not on the slide release

[gregthehand]

I'll look at my grip as soon as I get home.

[gregthehand]

Well when you're right you're right. I checked out my grip amd sure enough I was riding that slide stop. It's going to take a
little training to get off of it. I have to move my thumb away from the slide a little but and it works just fine. I'll have a range report tomorrow after the Saturday WHIDPA match.

[Jumping Frog]

Maybe you want to edit the thread title to say: Shooter Malfunction.