Sub 2lb Trigger on an M&P

[DocMedic]

I am planning on setting it up with an 11lb recoil spring then using 200gr .40 rounds through it. It should shoot pretty soft with that setup.

Curious, did you pick up a fullsize M&P40 or did you get your hands on a M&P40pro 5"?

[RH45]

I tried a 13# recoil spring in my Pro, and if I shook the gun, it would come out of battery. I went back to the stock set up rather than take a chance of something nasty happening.

[CHA-LEE]

DocMedic> I couldn't find the 5" Pro .40 anywhere so I picked up a standard M&P 40. I figured that I would be swapping the sights and doing a trigger job anyway so why waste the extra $$$ on the Pro version? Using a 5" model has its trade off's. You get a longer barrel so you can technically use lighter loads and have the same fps. You also get a wider sight radious with the 5". But you also end up with a heavier slide which in Production shooting mouse fart loads isn't a good thing

[CHA-LEE]

RH45> To get away with using a lighter recoil spring you have to also use a lighter striker spring. Since the recoil and striker springs fight each other when its cocked there will always be a somewhat loose lockup. The trick is finding out how soft of a striker spring you can use before you start getting light primer strikes. I am sure that I will be in for quite a bit of trial and error to figure out the magical spring combo that works reliably. But being able to use a 11lb recoil spring would be an advantage due to the reduced muzzle flip.

The XD's run into the same issue due to their similar striker/sear engagement design. I was told that I couldn't run less than 14lb recoils springs in those due to the weak lockup but some how I was able to get a 10lb recoil spring to work just fine and still have solid primer hits

[fiddler]

Hey CHA-LEE, how about some pics of what you did to your trigger. I'd like to see where you put the set screws.

[CHA-LEE]

I will see if I can take some pic's of my handy work in the next couple of days. I want to hold off on taking any pic's of this stuff until I get it all done and know that it actually works

Edited October 7, 2010 by CHA-LEE

[RH45]

RH45> To get away with using a lighter recoil spring you have to also use a lighter striker spring. Since the recoil and striker springs fight each other when its cocked there will always be a somewhat loose lockup. The trick is finding out how soft of a striker spring you can use before you start getting light primer strikes. I am sure that I will be in for quite a bit of trial and error to figure out the magical spring combo that works reliably. But being able to use a 11lb recoil spring would be an advantage due to the reduced muzzle flip.

The XD's run into the same issue due to their similar striker/sear engagement design. I was told that I couldn't run less than 14lb recoils springs in those due to the weak lockup but some how I was able to get a 10lb recoil spring to work just fine and still have solid primer hits

That was WITH a reduced power striker spring.

[CHA-LEE]

RH45> You are correct. I will be using a reduced power striker spring on the M&P as well. This is where a lot of the trial and error testing is needed. Figuring out how light I can go on the striker spring is going to take a little bit of testing to figure out. We will see how it goes once I hit the range and start testing things out.

Edited October 7, 2010 by CHA-LEE

[CHA-LEE]

Well I got my APEX goodies today so I dug into this bad boy once again. Since I had already modified the stock sear and firing pin plunger I didn't intall the APEX parts. I instead installed the APEX Competition springs. The only modification I made to the new springs was to cut a couple of coils off of the striker spring as it was a mile long. After installing all of the parts and putting it back together it felt awesome. The trigger has a little bit of take up until you hit the wall of the sear and then only a little more effort is needed to push through the sear and drop the striker. It feels pretty close to my EAA Limited gun. Now it was the moment of truth........ I broke out the trigger pull gauge and checked it out multiple times. It came out time after time at a consistent 1.75lbs

I am going to head out to the range tomorrow to give it a live fire shake down run to see how it works with the minor loads I built up for it. I still need to sight in the new Dawson sights and fine tune the recoil and striker springs. But so far I am very pleased with the results

[mike cyrwus]

make sure you bust off a few quick splits and a bill drill or two.

[High Lord Gomer]

I have experienced light primer strikes on a few M&Ps after only a thousand or two rounds so I run nothing but extra-power striker springs in mine. I (sort of) understand your comments about balancing the striker and recoil springs but I just want it to go bang every time and I'm not too concerned about a little harder trigger pull.

[CHA-LEE]

Here are some pictures of the pre travel and over travel set screws that I installed.

This is a 2-56 cap head screw that I installed in the center of the trigger. The cap head butts up against the frame to limit the pre travel.

This is another 2-56 cap head screw that is installed in the frame. I installed it a little more forward than it should be so I could turn down the outer diameter of the cap head to make the over travel setting perfect. Polishing the head also allows the trigger bar to slip across it when the sear resets and you are mashing on the trigger. I am not sure if the small diameter 2-56 is going to hold up or not under extreme shooting conditions but I will find out shortly. I wanted to start small and work my way up as I can just as easily install a 4-40 screw and achieve the same thing.

[CHA-LEE]

The shooting gods smile upon me today. I took the M&P to a local indoor range today and ran it through its paces and it ran perfectly. The sights were right on the money so no adjustments were needed so that was an extra bonus. We shot about 200 rounds through it with most of it being done by my lady and it worked great with no issues at all. I think that the rounds I built are still a little too spunky for Minor Power factor but I won't know for sure until tomorrow when I can actually chrono some rounds. Tomorrow I will be shooting at a private outdoor range so I can give it a through run for its money in real match conditions.

So far though I am really happy with how it turned out but more importantly my lady really likes shooting it so that is the true litmus test. She likes it so much that she wants to shoot it this Sunday at the local USPSA match

I am going to declare the sub 2lb M&P Trigger project as - MISSION ACCOMPLISHED !!!!

[RH45]

The shooting gods smile upon me today. I took the M&P to a local indoor range today and ran it through its paces and it ran perfectly. The sights were right on the money so no adjustments were needed so that was an extra bonus. We shot about 200 rounds through it with most of it being done by my lady and it worked great with no issues at all. I think that the rounds I built are still a little too spunky for Minor Power factor but I won't know for sure until tomorrow when I can actually chrono some rounds. Tomorrow I will be shooting at a private outdoor range so I can give it a through run for its money in real match conditions.

So far though I am really happy with how it turned out but more importantly my lady really likes shooting it so that is the true litmus test. She likes it so much that she wants to shoot it this Sunday at the local USPSA match

I am going to declare the sub 2lb M&P Trigger project as - MISSION ACCOMPLISHED !!!!

Cool!!

[CHA-LEE]

Well I beat on it today pretty good running another 200 rounds through it and it ran like a champ. Zero issues so far. The .40 rounds are only a little too hot so the next batch I will drop the powder a tenth of a grain. Its all ready for the match tomorrow and I am looking forward to seeing my lady have fun with it.

[CHA-LEE]

My lady used the new M&P at the local match this past Sunday and it ran flawlessly. I also had a bunch of people shoot it after the match and they all liked it a lot. With about 600 rounds down the pipe and about 10 different people shooting it without one issue I am going to consider this project a success. Listed below are the parts I used for this build along with the load used.

Standard M&P 40

Dawson FO front sight, .100 wide X .180 Tall

Dawson Fixed Target rear sight with .130 notch

Speed Shooters Specialties Tungsten Guide Rod

ISMI 11lb Recoil spring (With 2 coils cut off)

APEX Tactical Competition Trigger Spring

APEX Tactical Competition Striker Spring (With 4 coils cut off)

2-56 Cap Head screws for setting pre/over travel

.40 Minor load details

Bullet – Montana Gold 200gr .40 S&W CMJ

Powder – Clays, 3.1gr

Primer – CCI Standard Small Pistol

OAL – 1.14

Average FPS – 650

Average Power Factor - 130

[hanexp]

Your M&P is proof positive that something can be both sweet and bhadhass at the same time. Trigger is very light and crisp with good reset and the sights track consistently. Thanks for the time with your M&P. Very impressive!

It was equally good to meet Ms. Panda (first time for me). I hope she shoots eats shoots & sticks around the range!

[zero-down]

Cha-lee, what do you think the total trigger travel is with the set screws? Is there any trigger prep or is it right there?

Edited October 11, 2010 by zero-down

[CHA-LEE]

Zero-down> I will have to measure it but I built it with a little bit of take up before it starts touching the sear. Then you push through the sear only far enough to drop the striker, which isn't much trigger movement. I will measure it tonight and post up the results. I can't stand it when there isn't at least a little bit of take up before it hits the sear. Without this its really hard to know exactly when its going to break for precise shots.

[DocMedic]

I got to play with Cha-lee's Trigger job on the M&P40. A lot of take up was removed, almost to the point were it felt a little scary to me . Trigger safety would still be activated which was nice, but after that it didn't take much movement to break the shot off. Just enough to disengage the trigger safety lip then BAM! Sweet shooter for sure.

[CHA-LEE]

Cha-lee, what do you think the total trigger travel is with the set screws? Is there any trigger prep or is it right there?

Ok I measured the trigger travel. From initial trigger rearward movement to touching the sear its 2.5mm of movement. Then as you push through the sear its another 1.7 mm until it breaks and drops the striker. Then from fully pulled back moving forward to sear reset its 2mm. So the overall trigger travel from front to back is 4.5mm. I use millimeter measurements because its easier to communicate than inches. There are plenty of millimeter to inch calculators online if you want to figure out these measurements in inch values.

I am not sure what the stock travel distances are as I didn’t measure it before starting the trigger job. But this trigger has significantly less pre travel, over travel, and reset movement distances.

[Six]

How much of a difference would you say cutting the Apex striker spring made? Did you try a before and after?

[CHA-LEE]

How much of a difference would you say cutting the Apex striker spring made? Did you try a before and after?

Cutting coils off of the striker spring makes a little difference in the trigger pull but the majority of the change can be felt in the lockup of the chamber when its cocked. Reducing the tension of the striker spring reduces how much it fights the recoil spring when its cocked. This allows you to run a lighter recoil spring and still maintain a decent lockup of the chamber. I cut 4 coils off of the APEX competition striker spring, which is a significant amount of change in length. It still gets solid primer strikes on CCI primers, which are known to be a little harder than others. If I was using softer primers, like Federals, I would try cutting more coils off of the striker spring to make the chamber lockup even more solid.

[fiddler]

Here are some pictures of the pre travel and over travel set screws that I installed.

Thanks for the pics

[Leozinho]

I think running a sub 2lb trigger in a gun with no safety is insane.

JT

The gun has a safety, its built into the trigger. Safety starts with keeping your booger picker off the boom lever. This applies to any gun so why would it be any different with this one?

I'm with JT on this. By your logic, a 2 oz trigger would be completely safe, right? Making glib comments about keeping the finger of the trigger is fine, but the problem is that we don't always keep our fingers off the trigger. Better shooters than you and me have had NDs and even shot themselves even though they preach keeping keeping their fingers off the triggers too. I've seen good "safe" shooters' fingers get on the trigger at the wrong time, and a safety or a few pounds of pull might have been the difference between a bad accident and nothing.

Not to mention that things other than fingers can also pull the trigger. A few extra pounds might be the difference between a round through your thigh or you realizing in time you snagged your shirt in the trigger guard when reholstering.