Not sure what forum this belongs in (M&P trigger question)

[MXD]

Sorry if this is in the wrong forum but I could not find a gun smith forum.

I posted this over on MP-pistols.com but maybe you guys can help me. Long story short, I had a trigger job done and was told it 4.5-5#. It still felt a bit grainy so I figured I would pull it apart and look for a bur or something minor. Many hours later, I filed a bit more and re polished and now it's way too light. I don't know what it measures but the 4.5# felt more like the 10 it originally had and now it feels like a fraction of the weight. I love the way it feels but I'm afraid it might be a bit dangerous for a carry gun. Is there an easy way to put some weight back in it or do I need to buy a new sear? Also, can you work the sear enough that it would release the striker with just the striker spring pressure (in other words, not a trigger pull, but just the sear not being able to hold the striker)? I realize the striker plunger would stop it from happening but I just want to be 100% sure.

I suppose I should measure it first but if it feels too light I guess the number is irrelevant.

Any suggestions?

 

[MXD]

OK, I just hung a plastic bag from a coat hanger and ran the coat hanger through the trigger and put a 5# weight in the bag. I tried to run the coat hanger as far down the trigger as I could for leverage and it would not break. I could easily get it to break if disrupted the gun at all but just hanging idle, it would not break

 

[Supermoto]

what part of the sear did you work? if you do not have enough engagement on the sear/striker, less than .028" than the gun will not be safe.

 

[SA John]

Did you shorten the engagement hook on the striker? If you did, you are screwed. A proper job on the M&P does not include shortening this vital dimension. If you left the hook normal length and took off the "bump" you might be able to file a negative angle back on the striker hook to make it grab better and not slide off so readily, but I suspect you're porked. Others may have better ideas. I only messed with mine and had good luck with it. I felt very lucky for I had not worked on one previous. Usually l wonk the first job I do on a new design.

John

 

[Cross-X]

Send a PM to Greg Derr. He is a gunsmith with a dealer listing here on NES. Does wonderful work. www.derrprecision.com

Darius Arbabi

 

[SA John]

Just remembered, the "bump" is on the sear. Rework the sear if you flattened it out. And never listen to internet gunsmiths who can't remember what the hell they are trying to describe. That is my very best advise.

John

 

[MXD]

I did not touch the "thickness" of the sear from north to south (as it sits in the block), only filed and polished the hump on the face of the sear that contacts the striker, filed off some of the hump were the sear contacts the trigger bar, and I polished the corresponding face on the striker but I did not "shorten" it so theoretically, it should be the same contact area

 

[Supermoto]

When you change the angle of the sear/trigger bow, you can add creep depending on the angle.

On the hump were it contacts the striker, mark the striker and sear with a sharpie, dry firy the gun a few times, see how much and how the engagement it

 

[MXD]

Just remembered, the "bump" is on the sear. Rework the sear if you flattened it out.

If you look at a cross section of the sear were it contacts the striker, it has a dog leg angle in it to get it to bite the striker. I filled that down so that the dog leg is gone but it is not perpendicular to the top edge (i did not file it to 90 degrees). It still angles into the striker but its one face now instead of 2. Does that make sense?

 

[MXD]

I just scribbled with a sharpie all over the faces of the sear and the striker where they meet. The ink on the striker was untouched except for the top edge which means it is scraping the sear but not mating face to face. as far as the depth, the sharpie was wiped clean from the top of the sear to .1cm (.039 inches) down from the top.

 

[SA John]

MXD: I understand what you did and the way you described it. You've exchanged the original bearing surface on the sear (the hump) with the new surface (flat trailing edge). I really don't know what to tell you from here if it is not feeling right. Can't put metal back and if you start putting a larger radius on that trailing edge, you are essentially shortening the engagment length. Still, you might try that - rounding the trailing edge of sear. But first you should write to S&W asking for a new sear because your wife or girlfriend just took your gun apart (in an effort to impress you) and lost that vital item. Then you can start all over again.

Sorry,
John

 

[MXD]

Thanks john for your help. As far as how it feels......it feels great! Positive reset, light pull, consistent, and smooth. I'm just not sure if it is safe for a carry gun. I might have done too good of a job. I will pull the sear out and order a new one just in case.

As far as the striker "scraping" the sear, is that correct or should it be the other way around or should they mate face to face?

 

[CRSIII]

1911. (flame on!)

 

[SA John]

All sear releases are drag releases. Some are just longer than others. If you have full-length sear/hook engagment, I'd not worry about it popping loose by itself. You still have a firing pin block that has to be moved by pulling the trigger. So it isn't going to fire no matter what you did to the sear/hook unless you clear that firingpin channel by pulling trigger. If you like what you have, be happy and go forth and shoot that bad boy.

John

 

[MassBites]

MXD: I understand what you did and the way you described it. You've exchanged the original bearing surface on the sear (the hump) with the new surface (flat trailing edge). I really don't know what to tell you from here if it is not feeling right. Can't put metal back and if you start putting a larger radius on that trailing edge, you are essentially shortening the engagment length. Still, you might try that - rounding the trailing edge of sear. But first you should write to S&W asking for a new sear because your wife or girlfriend just took your gun apart (in an effort to impress you) and lost that vital item. Then you can start all over again.

Sorry,
John

Oh sure. Always blame it on the woman. Why can't he just say his dog ate the sear? Huh?

 

[SA John]

MassBites: I watched my father take a bag full of Parker shotgun reciever parts to an old gunsmith in Georgetown Mass. years ago and tell the guy my mother did this, and could you put it back together. The gunsmith was not amused. I was 10 at the time and thought it was funny as hell. It was the only time I saw my dad fail to put a firearm back together properly after reblueing. Turns out he needed a special jig to compress the firing springs. He didn't have that tool but the humorless gunsmith did.

John

 

[MXD]

I fired 200 rounds through it today and it worked great. No issues whatsoever. My groups tightened up too with the new lighter trigger. Maybe I'll just leave it alone.