S&W M&P 9 Slam Fire

[pastordigger]

Greetings, all!

My brother, racking the slide to chamber a round recently, and without his finger in the trigger guard, experienced a slam fire that, fortunately, did not harm anything but the workroom's plywood floor.

My question is: what could cause this? I've already told him he should have it looked at by a gunsmith at the very least. Maybe ship it back to S&W?

Thanks for your help.

 

[LNK]

Was it a reload with a high primer? Or factory ammo. If factory, get it checked....

 

[The Lone Haranguer]

Retract and lock back the slide and see if the firing pin protrudes through the breechface hole. It should not.

 

[pastordigger]

Thanks for the responses.

First, it was with factory ammo, not reloads.

Second, when I see him again next week I'll take a look and see if the firing pin is protruding.

Either way, I'm sure he's going to take it to a gunsmith before he does anything else with it.

 

[tahunua001]

I recently saw one guy on XDtalk saying the same thing about an XD9 and everyone insisted that he had his finger on the trigger while he insisted that his finger wasn't even near the trigger. all I know is that if you know for certain that it wasn't an accidental trigger pull then the only option left is a mechanical failure. racking the slide should have the exact same effect as normal cycling. so if it does this then in theory it would eject, rechamber, and accidentally fire again so in it is possible that your brother could in fact be on the verge on owning the very first full auto M&P pistol and he wont exactly like it if it happens again while it's not being aimed down range. the firing pin is the most likely culprit.

 

[chris in va]

I would think the firing pin block would prevent slam fires. Something is definitely not right.

 

[bdb benzino]

I hate to say it, but some people either don't realize or don't want to admit they caused an ND. Hope that's not the case here. Get the pistol checked out.

 

[wally]

Unless there is a mechanical defect, meaning it'll do it again next time a round is chambered, I'm betting his finger was on the trigger and he tightened his grip when the slide slamed home.

If the gunsmith finds nothing amiss, this is the only viable explaination, anything else is denial.

Learn from the mistake, and be thankful it was at least pointed in a safe direction.

 

[easyg]

I would send it back to S&W instead of giving it to a gunsmith.

 

[pastordigger]

Thanks for all of the other replies, folks.

As to the "trigger accidentally on the finger" thing -- I was actually observing him (don't remember if I failed to mention that) at the time, and he did not have any finger in the trigger guard. I was as startled as he was when the weapon discharged.

Fortunately, it did not keep going (a la "full-auto"), as there were 9 more rounds in the magazine. The whole scenario confused me, and is one reason why I insisted that he take it to a gunsmith, at the very least. Something just wasn't right...

Thanks again.

 

[voyager4520]

I don't know too much about the M&P design but know that it's similar to Glock in a few ways. If the trigger spring(or trigger bar spring) is weak that could cause it. Also if the sear or firing pin lug are worn so that there's not enough sear engagement, that could cause it. Tell him to call S&W.

 

[Jackal1]

Not sure how the M&P is designed, but here's something to check:

On the XD-45: when the striker retaining pin breaks and the slide is subsequently retracted the sear pushes the firing pin way out through the breech face. The pin protrudes so far, in fact, that it extends above the next round in the magazine and inhibits it from loading. And, no, the firing pin safety does not reliably work when the retaining pin breaks. This designed-in failsafe feature prevents any sort of slam-fire situation should the striker retaining pin break.

I hope the M&P has a similar feature.... If it does or does not, let us know!