Another M&P40 1.0 Issue -

[revchuck38]

I did a couple of classes with KRTraining yesterday, Defensive Pistol Skills 2 in the afternoon and a low-light class in the evening. I was using the M&P40 1.0 with the ejection issues; it worked fine during the afternoon class but at the start of the low-light portion it turned into a single-shot - the slide locked back after each shot. I switched to my other M&P40 1.0 that I bought new when they first came out and finished the class with no further drama.

I field-stripped the offending gun this evening and checked the slide stop. It's still in one piece, but when you rotate it up it just kinda moseys on back down. I field-stripped my M&P45 Compact and rotated the slide stop up and it returned under firm spring pressure. I hit the internals on the 40 with spray RemOil (because it's the only spray cleaner I have) and it didn't help, though it did flush out a bunch of crud.

MGW has the part. Brownell's has one too, perhaps a newer version? The spring shown on the new part appears to be broken off on mine. How hard is this to replace? YouTube and Google aren't much help. It looks like you have to remove the inner chassis to replace the slide stop.

[JAH 3rd]

This is a S&W Shield EZ that is being completely disassembled. Look at the 11:00-14:00 minute part to answer your question. As you stated, the locking block needs to be removed to access the slide stop. This video may help.

https://www.youtube.com/watch?v=sGWndzZkJfg

[JAH 3rd]

Here is a better angle with an actual M&P.

https://www.youtube.com/watch?v=EHGhgco1Cs0

[revchuck38]

I've got another slide stop and trigger return spring, plus an ejector and extractor spring for the ejection issue, on the way from MGW. I'll see how this goes...

[JAH 3rd]

Keep us updated on your progress once your parts arrive. What you've ordered are consumable parts that need replacing in pistols with high or unknown round counts. Good luck!!

[revchuck38]

So I got those parts and while I was trying to install them, the loose pin in the sear block that holds the magazine safety came out and I lost a couple of the springs that were on that pin. I ordered another sear block (without the magazine safety) and finally got it in there. Now the trigger is much heavier and the sear doesn't release until the trigger is all the way to the frame...and sometimes not then. I found that when it won't release, flicking the thumb safety on and off will let the sear release on the next attempt.

I've obviously screwed up the reassembly. Suggestions?

[idahojess]

So I got those parts and while I was trying to install them, the loose pin in the sear block that holds the magazine safety came out and I lost a couple of the springs that were on that pin. I ordered another sear block (without the magazine safety) and finally got it in there. Now the trigger is much heavier and the sear doesn't release until the trigger is all the way to the frame...and sometimes not then. I found that when it won't release, flicking the thumb safety on and off will let the sear release on the next attempt.

I've obviously screwed up the reassembly. Suggestions?

Maybe check out the Apex tactical video channel? They will show how to install their parts, which should be similar to reassembling with factory parts. They've done a number of videos on the M&P over the years.

[revchuck38]

^^^^That's the video I used to put it back together. I'll take the gun apart tomorrow and try again...gotta figure out just how to hold my mouth right.

[JAH 3rd]

First of all, what I am about to say, I've never done before. It is just an observation from how the M&P 1.0 engages the sear. I've looked at my 1.0 to refresh my memory.

So with absolutely no magazine or round in the chamber, take the slide off the frame. I use the sear deactivation lever to drop the sear so the slide can come off the frame. So push the deactivation lever back towards the frame as it would be when the pistol is carried. Look at the video idahojess posted and stop it at the 2:24 mark. You will see the trigger bar. Look at the end with the little loop, often called the candy cane. Now if you pull the trigger slowly several times, you will see how the loop engages the sear and drops it at the rear most of the trigger pull. So if the loop is too small, it will engage the sear later in the trigger pull. If the loop is larger, it will engage the sear sooner. And this adjustment is very slight to the loop to affect the engagement one way or another. So I wonder if the loop needs an adjustment, albeit very slight, to fine tune the dropping of the sear. After all, we are talking new parts and tolerances of old and new parts.

I looked at the point where the sear falls on my 1.0 and it is at the rearmost of the trigger pull, with no over-travel at all.

Hopefully others will chime in with their observations. Once again, I post this info just from my observation of how the sear is released in the 1.0 M&P. The 2.0 sear release does away with the candy cane on the trigger bar.

[Spartan1980]

Regarding the candy cane loop. I've long since forgot the measurement spec but you can set it with a feeler gage. It makes it easy to know what you are doing, the effect it has, and guesstimating an amount to acquire a desired change.