Dead trigger after a solid mag change?

[BobRockefeller]

The basics: M&P Pro 5" 1.0 CORE, Apex trigger kit, factory magazines, 11# recoil spring

 

The problem: After a solidly seated mag change with one in the chamber (slide is in battery), the trigger is dead. I pull it, it's slack, and no bang. If I rack the slide back maybe ½", release the slide, and try again, I get a bang.

 

If I seat a new mag very gently while the slide is in battery, the trigger is fine. Slide lock reloads are fine.

 

What should I be looking for?

Edited May 18, 2020 by BobRockefeller

[FightFireJay]

It sounds like the striker is slipping off of the sear and the striker block is the only thing keeping the pistol from discharging.

 

Pulling the slide back resets the striker on the sear.

 

I think I'd start by checking or replacing the sear spring.  I'd also take a hard look at the sear/striker engagement surfaces for wear.

 

How many problem free rounds do you have through the M&P with these trigger parts?  Have you replaced any other parts recently (like the striker)?

Edited May 18, 2020 by FightFireJay

[ima45dv8]

If you have them, put the factory parts back in. If it stops failing, problem solved.

[Sarge]

I tried running an M&P years ago and I hated any changes. With an 11pound recoil spring I could hold the gun up and shake it out of battery. Could be the full mag is putting enough pressure on it to pull it out of battery.

13 pound was as light as it would run even close to reliable

[SGT_Schultz]

10 hours ago, BobRockefeller said:

What should I be looking for?

 

A CZ P-10

[Benevolence]

Sear spring too weak or trigger bar is getting pushed out from under the sear. Put more bend in the trigger bar perhaps. I would suspect the trigger bar. 

 

Take the slide assembly off, and see if you can get the problem to repeat itself. Maybe be able to see the problem easier that way. 

 

Edit; out of battery actually sounds likely as well. Does it fire if you push forward on the side after slamming a mag in? If so you’ll need to either increase recoil or decrease striker spring. 

Edited May 19, 2020 by Benevolence

[BobRockefeller]

3 hours ago, Sarge said:

I tried running an M&P years ago and I hated any changes. With an 11pound recoil spring I could hold the gun up and shake it out of battery. Could be the full mag is putting enough pressure on it to pull it out of battery.

13 pound was as light as it would run even close to reliable

 

I'm pretty sure this is the fix. Looking closely, I could see that the slide had been bumped very slightly out of battery when the mag was slammed home. I put a 13# spring in and saw no more problems on the bench with snap caps. I'll confirm it at the range later this week.