I’m having trouble with the trigger loop/sear engagement on an M&P9C.
At least that is what I believe.
M&P9C: 1400 rounds through it
H trigger bar
Apex hard sear (polished by G&R)
Apex ultimate striker block
Large sear plunger.
Last range trip, the effort needed to break the shot increased to the point that I couldn’t fire. This was after about 40 shots. Field stripped, saw no issues. Reassembled, same problem within a few shots. The striker and sear are staged to fire, but the trigger pull weight increases and will not operate the sear. The trigger bottoms out without affecting the sear.
Unloaded, dry fire will do the same thing. Sometimes it works a few times, then the pull weight increasees until it no longer functions.
Disassembled and cleaned sear block, dry fire produced same results. Sometimes a few functional trigger pulls, then the same problem. I noticed that the trigger loop/sear engagement is rough.
If I pull the slide back slightly while pulling the trigger, the sear releases the striker.
I also have a full size M&P9 (4800 rounds, same internals as the compact). With the slide removed, the trigger loop/sear engagement was smooth. I swapped sears between the two. Result: both pistols experienced the same problem after less than 100 dry fires.
I then swapped trigger and trigger bars (sears still swapped). Same problem.
I then put all parts back in the original order. Now both pistols exhibit the same problem.
With the slides removed, the sear and trigger loop engagement is rough. Only the compact’s engagement was rough prior to swapping parts. Both pistols now will not release the striker. Both will release the striker if I pull back slightly on the slide.
Was the compact’s sear damaged, and then damaged both trigger loops?
Will a sear and trigger bar replacement be enough, or do I need to check something else?
Anyone ever had this problem?
Neither pistols had any problems prior to this.
Thank you for taking the time to read this long post.
Pics of compact parts prior to my “experiment”
try to bend the loop open just a little at a time until it functions. If u have feeler gauges it would help u know where your at with it. Hope it helps
Since you have been taking it apart, could it be that the trigger bar is too far in towards the sear block? There is a slot cut in the sear block for the tail end of the trigger bar to move with in.
I haven’t gotten a chance to measure tolerances, but I was looking at the photos I took last night. The wear inside the slide from the trigger bar is much heavier than I would expect. This is the compact slide. The full size slide (with 3 times the use) has much less wear than this.
OK thanks for the info. I’ll look up how to adjust it.
Do you find it odd that the pistol worked fine for so long (about 1000 rounds)?
Was it slowly damaging itself until the condition got to the point of failure?
Tolerance stacking would be my guess (as it wore in). Without actually holding it in my hand, it is hard to say for certain what happened. With that said, all trigger bar loops get adjusted when we build an M&P with Apex SEAR’s.
If you watch the video, Randy does about 11 thousandths (total). I generally look at the engagement with the trigger bar to sear with the slide off and adjust from there (read, eye ball it). Less is more here as you can open the loop too much and it won’t go under the sear.
It appears that Grant and others already took care of this but I also feel your trigger bar loop is not adjusted properly. The video already referenced gives good instruction, just make small adjustments. Don’t go crazy.
