S&W M&P-40 Magazine retention issue

[kodiak]

Hey all, this is an appeal to the calguns brain trust to help me out with an issue I'm having with my M&P40.

The magazine is dropping out during firing - not to the point of actually hitting the floor, but slipping down about a half an inch. This results in FTF, solved with tap rack bang. It occurs over half the time at this point. I recently switched to WWB ammunition from CCI blazer brass. With the blazer brass, I went around 1000 rounds without any failure using the same grip. I've been thinking about this and I've come up with the following possibilities (in no particular order):

-limp wrist/grip
*finger hitting release button due to recoil
-i tried firing with one hand, fingers totally clear of the button and it still happened

-magazine retention mechanism is shot

-bad magazine
*i just two new magazines from S&W and tried them out, still happened

-ammunition
*as previously stated, this did not occur with the blazer brass. I just finished off my WWB, so I'll be going back to blazer shortly

When I changed the backstrap from medium to small/large, that seemed to help a little. Well, that seems to just about cover it. Any advice would be much appreciated, and anyone in Los Angeles is welcome to try it out at FiringLine Burbank, Angeles, LAX, or LA Gun Club whenever. Since I might be needed a gunsmith on this one, any suggestions to that end would be welcome as well.

[miles2912]

Hey all, this is an appeal to the calguns brain trust to help me out with an issue I'm having with my M&P40.

The magazine is dropping out during firing - not to the point of actually hitting the floor, but slipping down about a half an inch. This results in FTF, solved with tap rack bang. It occurs over half the time at this point. I recently switched to WWB ammunition from CCI blazer brass. With the blazer brass, I went around 1000 rounds without any failure using the same grip. I've been thinking about this and I've come up with the following possibilities (in no particular order):

-limp wrist/grip
*finger hitting release button due to recoil
-i tried firing with one hand, fingers totally clear of the button and it still happened

-magazine retention mechanism is shot

-bad magazine
*i just two new magazines from S&W and tried them out, still happened

-ammunition
*as previously stated, this did not occur with the blazer brass. I just finished off my WWB, so I'll be going back to blazer shortly

When I changed the backstrap from medium to small/large, that seemed to help a little. Well, that seems to just about cover it. Any advice would be much appreciated, and anyone in Los Angeles is welcome to try it out at FiringLine Burbank, Angeles, LAX, or LA Gun Club whenever. Since I might be needed a gunsmith on this one, any suggestions to that end would be welcome as well.

I would check warranty status and ship the weapon back to S&W for repairs. The pistol is clearly defective.

[AJD]

As mentioned above I would contact S&W about sending the pistol in for warranty service. There is a "mag drop" issue that some M&P owners have experienced in the past. There was even a huge thread over on the M&P forum with many members posting about it although I'm not sure if it is still there. Btw, I think there may have even been a couple members here who have experienced the same issue.

[choochboost]

With over 1000 rounds through it, your grip is not likely the problem. It sounds like your mag catch is toast. Call S&W, they will send you a shipping label, and will fix it. You could get it back as fast as a week.

The mag catch is just a couple bucks IIRC, but since the problem solution is more complex than just replacing the catch, I'd definitely send it in. This problem was limited to a specific range of pistols (no I can't give you more info).

[1911su16b870]

This is the third time I've heard of M&Ps dumping mags duing use. Other two times the firearm was sent back for repair, and received sans mag dump syndrome from the factory.

[Trendkill]

Had it happen to me......after 4000 + rounds in my MP40....I received the drops. To my knowledge.....the drop issue has been resolved. I sent my MP in and had it back in a week + a free mag. There was a run of MP's that were made that had the drop issue....they show up here and there....not so much anymore.

[RFB]

I had total mag dropout twice with a rental M&P...I thought it was my thumb positioning before gun malfunction?

My $0.02

RFB

[code33]

I've had the mag dump problem.
S&W is one of the few companies that cover shipping both ways.
Send an email to qa@smith-wesson.com noting the issue and request a UPS label by email. Include your contact info and SN of the gun in the message.

Ship the gun back only. Don't include any mags or the case.

[kodiak]

Update

Just a little update on this matter. I called S&W customer service and they are mailing me a new mag catch. I was hoping they would take care of the repair but this will do. Does anyone know how to replace the catch? I'm guessing it's roughly the same procedure as switching it from one side to the other.

[code33]

Yep, replacement is same as switching it; you have to take it out to switch it.

Some have replaced the mag catch spring as well with one that is slightly higher in tension

http://mp-pistol.com/boards/index.php?showtopic=10805

[kodiak]

Issue resolved...?

A few days after requesting my new mag catch from S&W QA, I received it and installed it. Since then I have put 240 rounds through the gun without any failure. I'm optimistic that the new catch should hold up for at least a few thousand more rounds. On an unrelated note, I tried out a S&W 686 and it was a blast.

Thanks for all the input and see you at the range.