AR Trigger work

Saltwater60 · Feb 12, 2020

Someone here sis it no can’t remember who. I remember the jist of the thread and it was basically don’t take off too much or it won’t be semi auto anymore. I say go for it. I have a spare and I thought of the same thing.
Other thing to consider Is don’t heat it up too much or you might change the tempering for the metal.
I’d start by hand or use a little polishing compound on a fabric dremel bit until you get the hang of it.
What finish is on your tigger kit?

@thewheels · Feb 12, 2020

Interesting project.
I'd just be happy with way less grit in the standard trigger.

My only experience was polishing the snot out of an old Mosin Nagant trigger once. Man, that thing was crunchy and annoying.

kev74 · Feb 12, 2020

I made up a little jig for my mill that I can use to regrind the contour of the bottom of the hammer/sear, kind of making that shelf the trigger has to pull across shorter. So far, I've done 3 ARs and 3 or 4 10/22s with good results. Here's a thread about it:

AR Trigger Job

After putting the lower together on my NYGF AR build, I was left a little disappointed. I started with regular plain old DPMS lower parts kit trigger and hammer. The first thing I did was to massage the hammer and trigger by hand with some stones to try and remove the worst of the rough edges...

nygunforum.com

I might be the guy @Saltwater60 was referring to above. I thought I did one too short, but it turned out to be the disconnector was not so good. I swapped it out with one from another parts kit and all was well.

I've had people tell me the AR parts are case hardened and that a trigger job wouldn't last, but I haven't had one go bad yet. I don't shoot the ARs as much as I shoot pistols though.

Tisto · Feb 12, 2020

I've done several. I find that it is more beneficial to polish than to change the dimensions on any of the parts. A dremel tool with jeweler's rouge does wonders. Sometimes you may need to smoothe things up with a circle of 800 or 1000 grit sandpaper on the dremel first. VERY LIGHTLY, OF COURSE. After that, use the paper side, and then the felt wheel with rouge. A mirror finish makes for a fabulous trigger even if the travel is a little long. Be very careful not to get anything hot. You don't want to remove the temper. Don't mess with the springs, either. Leave them as they are. If absolutely necessary, purchase a set of lighter or heavier springs as you see fit. When you put it back together, be generous with synthetic grease. I can't do it right now, but tomorrow I will post pictures of what and where to polish.

Acer-m14 · Feb 13, 2020

@thewheels said:
My only experience was polishing the snot out of an old Mosin Nagant trigger once. Man, that thing was crunchy and annoying.

i did the same to my 91/30 mosin and bent the spring some to take up the 4 foot of trigger travel lol ..

did the trigger on my 270win Savage .. a little stone work and polish and playing with the spring tension ..

Saltwater60 · Feb 13, 2020

kev74 said:
I made up a little jig for my mill that I can use to regrind the contour of the bottom of the hammer/sear, kind of making that shelf the trigger has to pull across shorter. So far, I've done 3 ARs and 3 or 4 10/22s with good results. Here's a thread about it:

AR Trigger Job

After putting the lower together on my NYGF AR build, I was left a little disappointed. I started with regular plain old DPMS lower parts kit trigger and hammer. The first thing I did was to massage the hammer and trigger by hand with some stones to try and remove the worst of the rough edges...

nygunforum.com

I might be the guy @Saltwater60 was referring to above. I thought I did one too short, but it turned out to be the disconnector was not so good. I swapped it out with one from another parts kit and all was well.

I've had people tell me the AR parts are case hardened and that a trigger job wouldn't last, but I haven't had one go bad yet. I don't shoot the ARs as much as I shoot pistols though.

Yes Kev. That’s the thread I was referring to. Thanks for posting with such great detail on all tour projects.

BDinPutnam · Feb 13, 2020

Speaking for myself but probably others, I would love to see some before and after pics and/or the pics that @Tisto mentioned... I "owe" myself another build sometime in the near future and would like to do this as well.

Also agree with the comments re: springs, generally they're cheap enough to just pick up a different set of springs than to mess with the originals (but everyone is different, if you like to tinker have at it).

BDinPutnam · Feb 13, 2020

Super helpful, thank you sir!

:salute:

Tisto · Feb 13, 2020

Robin,
In the first picture you have posted, flatten and polish that surface, but leave the leading edge sharp.
In the second picture, do the same. The top edge is where the hammer catches and breaks from. A rounded edge here will cause all kinds of problems including doubles and failure of the hammer to stay locked. That edge NEEDS to be sharp, and is less than a 90°angle.
In the third picture that groove should be smooth and the edge to the right of it in your picture needs to be sharp. Do not round that over.
Be very careful not to remove too much material from any of those surfaces. A few thousandths of an inch too far and you will create safety issues. Assemble with generous amounts of synthetic grease. If you are anstalling anti-walk pins, don't forget to remove the J-spring from the hammer or it will hamper free movement. The J-spring can be a real bitch to remove, and once removed cannot be replaced ( you need to destroy it to get it out ) which means that that hammer must be used with anti-walk pins from then on.

meketrefe · Feb 13, 2020

Robin said:
I have an extra set of standard trigger parts and was thinking of experimenting with making it a touch lighter and with a cleaner break-off. I was wondering if anyone here has done this and knows of any pitfalls I might look out for. It is a pretty straight forward simple mechanism but there could be something I'm not picking up on.
I thought I would anneal the springs and take some of the preload out of them, re-temper, stone down some of the sear with a lot of trial and error. Seems thats all that required.
Robin

It depends on what you have to start with but a well made mil spec trigger can be tuned quite easily in a great smooth and crip trigger.
The firsr thing is to bend the hammer springs to loose some tension that in many cases is huge and totally unneecessary. In many cases it is actually worse than service carbines even when the triggers are actually better but the springs are way out of wack.
The next thing is to makensure you dont have any ridges from the cast in the hammer so a stone or even starting with a very fine file to make sure the bottom of the hammer is smooth and even a bit of a curve to make the group smoother when it starts moving.
But back ton the trigger, make sure there is no lateral up and down or side to side pkay that might indicate something out of spec.
Before you try anything even lapping force the trigger to conform to the hammer sear.
With the lower in your lap hold the hanmer with one hand while you slowly release the trigger. This will give you s feeling for the pull force and any creep. Before you tske it apart yet again to reduce or increase pull by forthwr conditioning the spring lets try to get rid of any creep. Put s drop of oil on the sear part. So pull the hammer forward as hard as you can and then stsrt pulling the trigger slowly. It will feel like 1000lbs trigger thst is ok since you are puling on the hammer forward like a cantilever until thr trigger breaks. The hand that pulls hard also prevents the hanmer from going free and damage the lower or even break the mag catch. The best part is to use the center of your palm kind on a concave shape so the back or your thimb pushes forward while the rest cstches the hammer at the same time.
Then repeat many times, cock and pull, cock and pull. Might have to do this several dozen times until you feel the extra torque is molding the engagement area one t o another. Visually inspect and make sure there is enough travel to engsge ssfely even with the reduced pull of the hammer.
So later you mihht also adjust the springbto make sure is not less than 3lbs or 3.5.
In some cases use a dab of very fine lapping compound but many times there is no need.
A stone on the sear area one shouldnbe very carefull.
If you dont feel comfortable consult with a gun smith.
Usibg this method, The 2 stage rra trigger becomes an amazing crip and smooth 2 stage trigger inline with triggers costing 2 or 3 times more.
Clean well and lube with a coulple of drops of quality motor oil.
Slow steps, carefull observation and patience are key here.
Good luck.

meketrefe · Feb 13, 2020

Oh I see you did some cleanimg to smooth tool marks. Very good but stop and do the above now.

tony · Feb 14, 2020

Am I imagining this or have I read somewhere that these trigger parts are case hardened and too much material removal will get you through the case down into softer material. Your sweet trigger may not last so long before it wears.

repete · Feb 14, 2020

Robin said:
I like to start with simple and if not satisfied, get complicated. I took the advise from Tisto and started simple by polishing the sear and matching notch applied some high end Mobil One grease, just a smear, and re-installed. I could not believe the difference!!!! It was not a bad trigger to begin with, just very stiff, thats why I thought retempering the springs would be beneficial. I don't think the will be necessary now. I don't have a measuring devise but it feels like I knocked off about three pounds and it has a very clean break. can't wait for a range day!!!
Thank you Tisto!!!!!!
Robin

If the trigger is to stiff try clipping about an 1/8 of an inch off the two ends of the trigger spring and reinstall, I took about 3/16" off and thought that was pretty good so tried another 1/8" and that was a bit to much so make sure you have more than one trigger spring.

repete · Feb 14, 2020

Forgot to mention, do a search on line . I saw a write up on using a set screw inserted into the pistol grip mounting hole that rduced the over travel. and reset time

Calculon · Feb 14, 2020

repete said:
Forgot to mention, do a search on line . I saw a write up on using a set screw inserted into the pistol grip mounting hole that rduced the over travel. and reset time

$9 at joebob’s

JoeBob's AR15 Grip Screw Trigger Adjuster

www.joeboboutfitters.com

meketrefe · Feb 14, 2020

Robin said:
Pretty much been doing just that Mek, thanks.
Robin

Perfect!. You are not going tobtotally get rid of the creep because of the design but it should become smoother with a predictable break.

repete · Feb 15, 2020

Calculon said:
$9 at joebob’s

JoeBob's AR15 Grip Screw Trigger Adjuster

JoeBob's AR15 Grip Screw Trigger Adjuster

www.joeboboutfitters.com

Thanks! Sure beats a 1/4" set screw!

AR Trigger work

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