S&W M&P Fail upon mandatory chambered reload. Fix?

Messy Pants

Messy Pants

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edit M&P 9MM Pro

So I shot my IPSC qualifier last weekend and had an all to familiar failure six times during the match.

After a Mandatory mag reload when a round is still chambered (slide closed), I insert the mag, aim and .... click nothing.

I rack the slide, eject the chambered round, and im back in business.

So. I believe the full 10 rd mag is in fact seated upon insertion but upon doing so it seems to bump the gun out of battery just a hair or something similar.

A final note: The gun and all mags were cleaned religiously on this as it is my competition gun and were lubed fully prior to the match.


A friend in the match said to me this is a common problem and that I should google it. I found some results but none I wanted to try without further info.

Please help with your experience and expertise.
 
M&P enthusiast here and I've never seen or heard of this either. Can you provide any more details? If it's going click as in the trigger breaks but nothing happens, that wouldn't be an out of battery. Have you tried recreating the problem at the range?
 
Never heard of it, myself, but I haven't looked.

My M&P9 4.25 slide needs to be pretty far back before the disconnector is activated. Did you reholster after the mandatory reload?

I did get one failure to fire with mine once in the middle of a string of fire: The ejected round had a very light primer strike, and the indent in the primer was clearly not centered. The round fired properly the next time I chambered it. This makes me think the gun wasn't fully in battery but the striker still struck. I use CCI (hard) primers, the gun was very dirty, and my practice handloads are not always uniform, if you know what I mean.

I don't see how seating a mag could case rearward movement in the slide, but I did notice that the mag followers for the M&P9 have excessively long legs (all the ones that I've seen). I trimmed mine quite a bit to get full mags to be able to seat without a ridiculous effort. Before that it took a double slap to seat them, so I'd run them with 9 rounds when I could get away with it.
 
Sambaru said:
M&P enthusiast here and I've never seen or heard of this either. Can you provide any more details? If it's going click as in the trigger breaks but nothing happens, that wouldn't be an out of battery. Have you tried recreating the problem at the range?
Click to expand...

I will try to recreate it at the indoor range. It is on every mag change when the slide is closed with a round chambered. We filmed the entire match and it did it 6 times. quick rack and it was fine after it shot the chambered round out. The mag is a little hard to put in and when is is slapped in it does the same thing every time.

i think it is the mags that need to be modified but I want to know how and where to do so if that is the case.
 
alpining said:
I did get one failure to fire with mine once in the middle of a string of fire: The ejected round had a very light primer strike, and the indent in the primer was clearly not centered. The round fired properly the next time I chambered it. This makes me think the gun wasn't fully in battery but the striker still struck. I use CCI (hard) primers, the gun was very dirty, and my practice handloads are not always uniform, if you know what I mean..
Click to expand...

the ammo was loaded on my dillon and every round was checked in a guage and calipre for the match.
 
Interesting problem. I am shooting M&P 9mm and never had that happen to me. However, I do have problem with the magazine follower. One of the magazine won't drop free when the gun is empty. Basically the slide lock tab that usually ride on the top of follower will get nudged to the side of the follower. Thus it doesn't give the spring tension to push the magazine out. I will have to manually pull the magazine out.

Some people says I can get replacement follower from Brownells that works better but haven't try that route yet.
 
alpining said:
Oh yeah, how many rounds on that recoil spring?
Click to expand...

I have 6 mags. not sure which ones were involved. will find out at range when i test it again. close to 5000 rounds on the gun and 3 of the mags i had since new and 3 have 1000 rounds on them. The 3 newer ones are stiffer though.
 
Messy Pants said:
I have 6 mags. not sure which ones were involved. will find out at range when i test it again. close to 5000 rounds on the gun and 3 of the mags i had since new and 3 have 1000 rounds on them. The 3 newer ones are stiffer though.
Click to expand...

I put different coloured dots on all my mags for exactly the same reason you have (identifying a problem one)
 
silverfoxdj said:
I put different coloured dots on all my mags for exactly the same reason you have (identifying a problem one)
Click to expand...

haha, I saw that people do something similar at the IPSC qualifier i shot at last weekend. Asked them why and they told me the same thing. So I immediately put a sticker with my name and a mag # on all my mags. Now I can easily see which magazine is the one that has the release problem.
 
Sounds like the dreaded 'dead trigger' - does your Pro have the old style sear block in it? - There were issues with dead triggers in the early Pro models, it's caused by the sear spring not having enough force to reset the sear, if you're using a "robust" slap to seat the mag, this type of sear spring can release the striker. The cure is a change to the sear block, to one that uses the current, larger diameter, sear spring. Sear blocks are available from Brownells, or try contacting Murray Charlton (Murray Charlton Enterprises) he may be able to send you one on warranty.

PS: All magazines should be paint marked with a number, also all optic settings and sight mount screws, knobs and latches should be marked to let you see if they're changing, failing or otherwise falling apart.
 
You may have to trim your mag followers some. 10 rounder M&P mags are known to have problems seating when 1 is in the chamber. I've seen and heard first hand from other IPSC shooter's using the M&P.
 
You may have to trim your mag followers some. 10 rounder M&P mags are known to have problems seating when 1 is in the chamber. I've seen and heard first hand from other IPSC shooter's using the M&P. Probably what your friend meant by the comment of it being a "common problem".
 
I own 4 MP pistols 9/CORE 9/ 45 an 22

on all my newer mage i cut two coils off the bottom of the mag spring
 
hmmm, instead of cutting the followers or cutting the springs why not try running 40cal mags in it?
i know they fit in the 9mm fine.
i also know they hold 12 9 mm rounds.
so if you loaded them with 10 there would be a a lot of room still in them, thus them not being so tight when you try to slap a full 10rd mag in.

i dont shoot comp but i do have a M&P 22, 9, 9 CORE, 40 and 45 and i noticed that the 40cal mags fight in the 9mm.

might save you doing alterations.
im kinda interested in this problem.
i have a brand new 9mm Pro CORE and i think ill to test this at the range next week to see if i can duplicate your problem.
 
have you modifed your followers yet?
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Are you sure you slide is fully forward when you pull the trigger. The M&P will trip the sear when the slide is slightly out of battery. There isn't enough force to set off the primer and it may not even dent the primer. Try some factory and see if happens.

Take Care

Bob
 
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