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Wow, AR 15 trigger job.

Discussion in 'Gunsmithing and Repairs' started by coolluke01, Nov 11, 2012.

  1. coolluke01

    coolluke01 Well-Known Member

    I went out shooting with my DPMS Sweet 16 the other day. I was able to consistently get 1.5"-1.75" groups @100 yards. I did get a 5/8" group once! My fingers where getting a little cold, it was about 30 deg. I was just using American Eagle ammo 55 gr FMJ. I was not happy with how the trigger was functioning. It was gritty and hard. After looking at $150-$200 triggers, I found this youtube video on trigger jobs. http://youtu.be/sJegVLr1rEU

    What a difference! I only tested it to make sure it fires but I'll be taking it out to the range this week. The trigger is soooo smooth and light. This is a very easy job to do. Just be patient and be careful. I sanded things with a tapered wet stone and a points file. The file is rather corse. A diamond nail file would be just perfect I think.

    Here's a pic of the 5/8" group. Gotta love a little luck right?

    Attached Files:

  2. rcmodel

    rcmodel Member in memoriam

    Thats good and all.

    But M16/AR-15 trigger parts are relatively soft steel with a hard surface heat treatment.

    If you cut through the hard surface with a stone or file, they will wear out really fast and fail to function properly, or safely.

    Did the YouTube guy mention that little detail?

  3. coolluke01

    coolluke01 Well-Known Member

    I had read about some one else asking that question. When doing a trigger job the goal is not to take off material. I just work out the tool marks. If you remove much material I can see that being a possibility. That treatment hardens the steel below the surface too, right? Now I understand that polishing does remove material, but it is so little and shouldn't effect the hardness of the parts, right?
  4. rcmodel

    rcmodel Member in memoriam


    But it is very shallow, and some tool marks aren't.

    It's pretty easy to not see the forest for the trees when getting that last little mark out with an ignition points file!!

    I'm just say'n, keep on eye on things for a while and watch for wear before you end up with a machingun, or worse..

  5. coolluke01

    coolluke01 Well-Known Member

    That file was far too corse and didn't get used after the first stroke.

    What would be the first sign of wear? Peening? Flaring? or will it be more subtle? It's hard to tell if the angle or edge of a part is changing, unless you have something to compare it too.

    I will take it apart after I shoot it next and check.

    It's great to have experience to keep us DIY'ers in check. ;)
  6. rcmodel

    rcmodel Member in memoriam

    I haven't seen first hand the results, because I won't do it.

    However if the hard surface has been compromised, I would expect some peening & visable wear where the disconnector, sear, & hammer hooks impact each other every shot.

    Maybe a real AR-15 trigger expert will happen along here pretty soon.
    But that guy isn't me.

  7. BBBBill

    BBBBill Well-Known Member

    With GI/standard commercial AR guts, it is counterproductive to try a trigger job for the reasons mentioned above, especially without proper stoning fixtures, stones, specifications, and the knowledge to do the work. Even then it is very iffy due to the variability of quality in the parts floating around out there. A youtube video sure doesn't impart the knowledge either. Best answer is purchase a quality aftermarket kit through Brownells, Midway, etc. There are several available at different price points. You get what you pay for. There is an old saying about paying for quality - "Buy once, cry once."
  8. Howard Roark

    Howard Roark Well-Known Member

    The depth of surface hardening varies greatly between manufacturers. I've drilled right through some and have had to use carbide tooling on others. Sooner or later trigger jobs like this go south. I didn't watch the whole video but some of these tricks include reducing sear engagement by either cutting down the sear depth or putting a set screw up though the pistol grip screw. All of these eventually cause the trigger nose to batter itself to oblivion. The question is where will the rifle be pointed when it slam fires?

    The best thing to do is buy a low cost trigger from someone like Compass Lake that has a hardened insert soldered into the trigger nose to prevent issues with battering.

    True two stage triggers avoid these problems by having the entire sear surface catch the hammer. Then the second stage stops the sear with little engagement left and offers resistance for the break.

    Hope this helps. I don't claim to be an authority.
  9. coolluke01

    coolluke01 Well-Known Member

    This is a very basic smooth out the tool marks. I didn't adjust or change any angles or depths. I can see how altering angles will cause unwanted problems.
    One thing I did was lighten the hammer spring. Simply bending it closed by hand reduces the force needed to disengage the sear. I didn't lighten it very much, but it made a big difference in the trigger feel and pull weight. I test fired it with two different brands of ammo and it functioned. I'll have to shoot a bunch to see how it functions.

    I figured if this didn't work, I could always buy new parts. Standard triggers aren't that expensive or I could just buy a target trigger too if need be.
  10. velocette

    velocette Well-Known Member

    You've been given some very good advice.
    It's up to you to decide the proper course of action.

  11. MtnCreek

    MtnCreek Well-Known Member

    First indication that my home trigger job was going south was when it started shooting doubles. This was maybe 1,000 rds after I buggered the trigger. It would occasionally shoot a double at first. A few hundred rds later, it would shoot once on pull and then again when slowly releasing the trigger. I replaced the fire control group with quality parts and left them alone.
  12. taliv

    taliv Moderator

    i refuse to do mods like this for reasons rcmodel outlined above, but i did once get a recall notice from a mfg asking me to return their hammer because their subcontractor had screwed up the surface hardening. when i looked at the hammer, sure enough, it was showing a lot of wear. it wouldn't have lasted much longer
  13. coolluke01

    coolluke01 Well-Known Member

    Thanks for all the input. I will keep a very close eye on it and watch for any deforming of parts. I suppose a new trigger will be on the wish list now.

    Does anyone have pics of what a worn hammer and sear looks like?
  14. adelbridge

    adelbridge Well-Known Member

    I have heard all the talk about surface hardening and such but every trigger assembly I have ever seen has been factory ground and the bare metal is exposed along with the tooling marks. The one thing I would be worried about is sear engagement and dropping the weapon. I my mind it is better to buy an aftermarket trigger that has been angled properly. G-Trigg is decent and under $100. If you have a lot of time on your hands, take the lower off and put some rubbing compound between the sear and the hammer and dry fire into a piece of cardboard for a few hours.
    Last edited: Nov 12, 2012
  15. BBBBill

    BBBBill Well-Known Member

    The two are not mutually exclusive. Most commercial AR triggers are patterned after the military triggers and are not given extra attention to give them a better trigger pull. The ground finish is apparent on the mil spec parts, too. That ground finish with the factory angles and depth of engagement is sufficient to give the trigger pull and longevity that is expected from a mil spec weapon. The surface hardening is thin and the efforts of a home smith can easily cut through that. Even if you don't cut through, the toughness can be reduced so that it fails much sooner than expected. It's as if you sanded the shell of an egg thinner. It might be smoother to the touch, but it will crack more easily from a bump.
  16. rcmodel

    rcmodel Member in memoriam

    They already went as far as they can go though.
    The final grind depth at the factory is factored in so they don't cut through it.

    But that doesn't leave much at all for the rest of us to whittle on later.

  17. rondog

    rondog Well-Known Member

    Just as an FYI - on a 1911 forum someone once mentioned that this company was giving away free gunsmithing stone kits as samples, so I jumped on board and damned if they didn't send me a set of their stones! These are "engineered abrasives", meaning artificial somehow, but they're damn nice stones and perfect sized for gunsmithing stuff.

    Now, if I only had the stones myself to work on my own gun triggers, hammers and sears, I could give you a better report. But I'm very impressed with the products they sent me, especially for free. I've used several of them for deburring and etc., and they work damn well. Won't take off any more than you want them to.

    I see they're priced here around $43.54, but who knows, if you mention that you'd heard of free samples they may hook you up. Worth a try.

  18. rskent

    rskent Well-Known Member

    I have had pretty good luck with AR trigger jobs. If you are careful with your stoning and you trim and bend your springs you can get a trigger that is reliable and isn't awful.
    What you can't get is a good trigger. Good trigger groups are expensive, but worth every penny. Just saying.
  19. coolluke01

    coolluke01 Well-Known Member

    I got out to the range for a little bit today. Boy that trigger is nice. I only shot 50 rounds or so. I checked for wear and didn't find anything. I'll have to keep an eye on it over the next 1000 rounds. Most likely will be summer before I can rack up that many rounds.

    It shot like a dream. We had a heatwave here today (40) so the fingers didn't get as cold this time.
    I had a few groups around 5/8 to 3/4" but most everything was around 1" to 1 1/2"
    I felt that the trigger was much easier to shoot well now. I'm sure I was shooting right about as well as the rifle with that ammo was capable of. I would bet it is a MOA rifle but not much better with bulk ammo.

    Here's my take on triggers. A lousy trigger will require you to take more time and be very deliberate and careful with your shot. A good/better trigger will allow you to make the shot quicker and with less effort. I do think I shot better with the trigger job and it was more fun. But it's not impossible to shoot well with a lousy trigger.In other words "It's Indian not the arrow"


    Attached Files:

  20. MtnCreek

    MtnCreek Well-Known Member

    Not impossible; I just haven't figured out how to consistently do it. Hope you hit it just the right amount and she holds up for you. Even if you did shorten the life of it, it's just that much sooner that you'll have a really nice trigger...

    Oh yea, you must have sent your cold weather down here cause it may not break 50 today, as opposed to 70. :)

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