Apex Striker Block

[MP40cMN]

Update on Striker Assembly not locking SB

Tonight I cleaned my three M&P .40's after a range outing this afternoon. This thread explained how my striker assembly didn't seem to be blocked by the striker block after dry firing. The pistol would shoot fine but if you locked the slide back after dry firing, the striker assembly could be moved all the way forward.

As I was doing a thorough cleaning, I pulled the striker assembly. I pushed the spring down and rotated the white plastic sleeve. I got it out of alignment when i released the spring. I then re-compressed the spring and rotated the plastic sleeve into the correct position. I re-assembled the pistol after completing the cleaning and checked how the striker assembly was functioning. Try as I might, I can't get it to fail. It is always locked by the SB now. I am guessing that plastic sleeve wasn't positioned quite right in the past. I had taken it out before but never played with the spring and sleeve. Now everything seems fine. I will keep an eye on it but hopefully the situation has been rectified and won't happen again.

 

[Dino1]

If it does this with either striker block, I would suspect there is a burr (or piece of debris) in the striker block channel causing the block to hang up and not return to it's rest position (or something is causing the striker not to return all the way back preventing the block from popping back. There's not a lot of "slop" in the striker movement forward. I can't move any of mine any distance forward until the block is pushed down (I checked both stock and Apex equipped pistols).

This... it is a very common problem with the M&P line due to the machining process. Check the striker block channel for a burr and remove it, it is probably their due to the procedure they use to drill the channels. Grind it out and polish it with very fine wet sandpaper, followed with a polish with some compound. You should have seen the burr in my 40c when I put the APEX kit in it. The factory block was scored on the side.