MP40C trigger issue

[milesr2]

I am having an issue where about one out of every ten trigger pulls (while dry firing) will result with the trigger pulled all the way back, and the weapon will not "fire." I have about 250 rounds through my mp40c with no issues prior to this. I have not used live ammo since discovering this problem. Does anyone have any ideas about what the problem could be?

 

[shawn mccarver]

"Short-stroking" or failing to allow the trigger to return forward far enough to re-set would cause the problem in live fire. For dry fire, however, the slide must be cycled each time you wish to pull the trigger. I know this will sound bad, but I have to ask - are you certain that you cycled the slide on those few occasions that it didn't "click" when it should have when you pulled the trigger?

 

[milesr2]

I'm positive. After I rack the slide, I pull the trigger all the way back, and it hits the stop and fails to "fire." I can then release the trigger and then squeeze again immediately, and then it will "fire." It's almost as if an internal mechanism isn't catching...

 

[Lee in Quartzsite]

After you pull the trigger the first time you must reset the trigger by cycling the slide...only needs to be moved to the rear about 1/2 inch. If you hold the trigger to the rear while you cycle the slide, then slowly let it return to its forward position you should be able to feel it reset on the sear.

 

[dajogejr]

How old is this pistol?

 

[milesr2]

I bought it new about 6 weeks ago.

 

[dajogejr]

Reason I asked, older ones, like mine...have a small sear spring which has been known to cause a dead trigger.
Yours certainly has the newer style.

 

[Prasko]

Sear flutter only happened during recoil. It wouldn't happen during dry firing.

 

[micocyco]

Have you broke the gun down / field striped it / cleaned it ?
Do you do it by the manual ?
For give my terminology , but there is a lever on the wife's M&P9c that it says you have to push down to remove slide & push back before putting it back on.
She for got to push it back up before putting the slide back on.
Had a heck of a time it working right again.

 

[milesr2]

I field stripped/cleaned it to smith and wesson specifications after my last range trip and have the takedown lever in the correct position... I've noticed this issue seems to occur more frequently with a slow, deliberate trigger squeeze.

 

[Lee in Quartzsite]

Have you broke the gun down / field striped it / cleaned it ?
Do you do it by the manual ?
For give my terminology , but there is a lever on the wife's M&P9c that it says you have to push down to remove slide & push back before putting it back on.
She for got to push it back up before putting the slide back on.
Had a heck of a time it working right again.

I believe if you read the manual it says the Sear Disconnect lever should be down when you reinstall the slide. Inserting a magazine will move it back to it's shooting position. Also keep the Take Down Lever in the down position when reinstalling the slide.

 

[micocyco]

I believe if you read the manual it says the Sear Disconnect lever should be down when you reinstall the slide. Inserting a magazine will move it back to it's shooting position. Also keep the Take Down Lever in the down position when reinstalling the slide.

Indeed you are correct , oops.

 

[micocyco]

I field stripped/cleaned it to smith and wesson specifications after my last range trip and have the takedown lever in the correct position... I've noticed this issue seems to occur more frequently with a slow, deliberate trigger squeeze.

That should not matter at all , I would get to the range asap & see how it runs.

 

[rcp1936]

Sounds like a failure to reset
https://www.youtube.com/watch?v=bdBpFlGtnFw

 

[Lee in Quartzsite]

AHHHHH, thanks, but no thanks. Don't feel like messing with the gun I depend on to save my life. Maybe with a target only gun..........

My M&P 45c functions like it should right out of the box.

 

[milesr2]

Another feature I just noticed is that in the case where the trigger is fully depressed while dry firing, and the weapon doesn't immediately "fire," if I keep the trigger depressed without resetting, it will discharge after a few seconds. I don't know if this sheds any more light on the issue...

 

[milesr2]

I think I might have figured it out. I experimented a bit and found that every time I get a discharge failure, if I field strip, the recoil spring is slightly dislodged from below the barrel. I think this is creating space between the trigger bar and striker safety, which disrupts the point of contact between the parts. The recoil spring looks a little jacked up, which might be why it is becoming dislodged from the notch in the barrel.