Trigger Failed to Engage

[Foofer23]

I went to the range today and flawlessly fired about 100 rounds in my M&P Pro. However, one round in particular wouldn't allow the my trigger to fully pull back and engage the firing pin. I was using white box 9mm Winchester 115 gr.

I ejected that one round, placed it in the mag, racked it, and the mag went fully forward with shell in battery. However once again the trigger would pull about half way back then stop like something was preventing it from moving. I didn't want to press it to hard for fear of breaking something. Any ideas what was going on? Thanks.

[Bkreutz]

Two possibilities come to mind
1. You're pulling on the top part of the trigger and not disengaging the trigger safety.
or
2. You're pulling on the trigger when you rack the slide which will not cock the striker.

The round will not have any effect on whether or not the firing system functions (it will function without a round in the chamber) so it has to be something unrelated to ammunition.

There are other possibilities (something mechanical) but your description brings the picture to me of the two possibilities that I mentioned. Good luck.

[Foofer23]

Originally Posted by Bkreutz

Two possibilities come to mind
1. You're pulling on the top part of the trigger and not disengaging the trigger safety.
or
2. You're pulling on the trigger when you rack the slide which will not cock the striker.

The round will not have any effect on whether or not the firing system functions (it will function without a round in the chamber) so it has to be something unrelated to ammunition.

There are other possibilities (something mechanical) but your description brings the picture to me of the two possibilities that I mentioned. Good luck.

Thanks for the reply. I know for a fact possibility #2 is not it! I never ever place my finger on the trigger until I'm ready to fire. Option #1 is a possibility. I saved the round and intend on taking it with me to the range soon. I sure am perplexed by it.

[Bkreutz]

Originally Posted by Foofer23

Thanks for the reply. I know for a fact possibility #2 is not it! I never ever place my finger on the trigger until I'm ready to fire. Option #1 is a possibility. I saved the round and intend on taking it with me to the range soon. I sure am perplexed by it.

Or it could be that the case on that round is longer than it's supposed to be, that would keep the slide out of battery preventing the pistol to be fired. Compare that round with another round. Take a look at this thread Unusual 9mm malfunction

[AGoyette]

Think of it this way.. If it is #1, at least you know that the trigger safety is working.

[Foofer23]

Originally Posted by AGoyette

Think of it this way.. If it is #1, at least you know that the trigger safety is working.

This is true. I have a hunch that it is the casing. I'm just glad that it wasn't a common problem with the rest of the ammo.

[Rastoff]

Originally Posted by Bkreutz

2. You're pulling on the trigger when you rack the slide which will not cock the striker.

This is not a possibility. Even if you hold the trigger back while cycling the slide, the sear will still be set. If it didn't, the gun would either go full auto or never fire a second round.

Full auto if the slide imparted enough momentum to slam the striker into the primer. Single shot uf it didn't. So, you see, the sear must reset even if the trigger is held back.

[Bkreutz]

Originally Posted by Rastoff

This is not a possibility. Even if you hold the trigger back while cycling the slide, the sear will still be set. If it didn't, the gun would either go full auto or never fire a second round.

Full auto if the slide imparted enough momentum to slam the striker into the primer. Single shot uf it didn't. So, you see, the sear must reset even if the trigger is held back.

I didn't think that one through. (actually if I had tried it on one of mine I would have realized that it didn't work that way. ) I was thinking about possibilities of the original problem. I stand corrected. I believe your other thread is most likely the cause though (too long of a case).

[Rastoff]

Originally Posted by Bkreutz

I believe your other thread is most likely the cause though (too long of a case).

The OP said the slide went all the way into battery. In the other thread, the "too long" case prevented the slide from going into battery. I mean, that could be the problem, but I would think it would be more obvious.

[Ruger_Up]

I actually had this happen to my 9c with the same ammo. I followed the same steps you did and just decided to pitch the round in the trash, which I later thought might have been a dangerous decision, but either way, same problem.
That's the first and only issue I've had with that pistol after 1000 rounds, so I chalked it up to an odd casing.


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[Foofer23]

A friend of mine who is a gun smith, took the round and measured it with a micrometer. The verdict is in; it is a bad casing.