DK Firearms

DIY AR Trigger Job

The #1 community for Gun Owners in Texas

Member Benefits:

  • Fewer Ads!
  • Discuss all aspects of firearm ownership
  • Discuss anti-gun legislation
  • Buy, sell, and trade in the classified section
  • Chat with Local gun shops, ranges, trainers & other businesses
  • Discover free outdoor shooting areas
  • View up to date on firearm-related events
  • Share photos & video with other members
  • ...and so much more!
  • LJH

    Well-Known
    Rating - 0%
    0   0   0
    Aug 22, 2011
    1,016
    31
    Austin
    Disclaimer: I, whatever site you found this on, or any other party is not liable for any damages or injury that may arise from anything YOU do, including anything you find in the following instructions. If you do any modifications you are solely responsible. If you’re not comfortable messing about with the guts of your fire control, then don’t do it. Use your head and a bit of common sense, if you think something is not working correctly then it most likely is not, and that is indeed a danger to you and everyone else.
    Perform a function and safety check after changing or modifying any part of any firearm ALWAYS! One last thing, do the test as described. If the trigger malfunctions or is not setup correctly it is damn dangerous.
    The last thing do not set your trigger to double on purpose. That’s just outright stupid as well as incredibly dangerous.
    I have been building AR-15s’ for a long time. It is a rewarding task that can be accomplished by almost anyone. These instructions can help take your building skills one step further than a simple assembly. If you follow the instructions you will be able to tune your trigger to get the very best performance using the factory parts.
    The single biggest flaw with Stoner’s rifle is the trigger. Most ARs’ come with a single stage trigger. The factory trigger is fine for home defense, or plinking, but for target use it is not optimal. The trigger pull is long, heavy, gritty, and in a word, sloppy. I am going to share my trigger techniques and it is not for the faint of heart. You will need to cut parts, drill and tap holes in the receiver, and generally take it on faith that this works. That is unless you have touched one of my triggers. If you have then you know it is worth the effort and you will end up with a trigger that feels more like a bolt action hunting rifle than an AR. Tuning the trigger is not hard, although it is time consuming. Just make sure you have access to a few spare parts. When you first start tuning the AR FCG it is not uncommon to ruin a part or two. The disconnecter tends to be the victim more often than any other part. The good news it is cheap. If you just remember to take your time and go slow, you won’t destroy anything. As my dad always told me, “you can always take more off, but you can’t put it back on.”

    Part 1) Prepping the lower for use of set screws.
    The lower will need a few changes in order to set the pre-travel and over-travel set screws. With use of the pre-travel screw you can get rid of the sloppy long pull. The over-travel screw stops the trigger from it long journey rearward once the hammer has been released. I personally find the over-travel more important than the pre-travel as a short over travel and reset give the trigger a better feel.
    Step 1 Using a 1/4" 28 tap, chase the pistol grip screw threads all the way through the lower. Use lots of cutting oil, and once again go slow and take your time. This will be used for the pre-travel set screw.

    chasewithtap.jpg

    Step 2 Drill and tap a hole for a over-travel set screw. I prefer under the pistol grip to the back of the trigger. (See photo for location)
    drillandtap.jpg



    Some alternative locations to drill and tap are under the trigger guard for both screws. Yes this is easier, I just like a little more surface area on set screws.
    toothin.jpg


    Step 3 Spring prep.
    In the following picture factory springs are on top, modified springs are on bottom.
    Trigger spring, about 1/16 of an inch from the “ring” or circle, bend both legs of the spring up slightly. This will reduce the "Pull" of the trigger. Don’t overdo it, you do need some pressure on the trigger or it will not reset. Without resetting it won’t go bang on the next shot.
    Hammer spring; this one is a bit tricky; I use two sets of needle nose pliers to adjust the angles. One set of the pliers goes through both sides of the ring. The second set is used to bend the wire. Pretty good amounts of grip are needed to keep the spring from turning in pliers. Try to keep the angles the same on both sides of the spring.
    (Some people who have done the “15 minute” trigger job and asked why I just don’t cut one of the hammer spring legs. I don’t like that due to the uneven pressure on the trigger pin. I also feel this method is conducive to a quicker lock time.)
    springfun.jpg



    Part 4 The Fire Control Group
    The following is a normal Fire Control Group.
    Using a buffing wheel and jewelers rouge LIGHTLY polish the contact points on the hammer, sear, and trigger. Really take it easy here, you are not trying to remove material, you just want to “shine it up.” The polish points are circled in the following photo. This will take some of the grit out of the trigger.
    shinecut.jpg



    Now it’s time to remove the spur from the hammer. I use a cut off wheel and a dremel tool. This is much easier than it looks. This lightens the hammer which reduces lock time. Less lock time, or the time the trigger is in motion, helps accuracy. Cut the spur where the arrow is. Once the cut is done, polish the hammer face. (the part that hits the firing pin)

    Now that everything is ready, assemble the lower except for the pistol grip, disconnecter, and the safety. You will get quite good at taking apart and putting the FCG back together.

    Part 5 The tricky part, adjustments.
    Once you have the parts installed, use a 1/4 X 28 half inch set screw to adjust the pre travel. To do this simply cock the hammer and run the set screw up the pistol grip screw hole. You are getting close when the trigger starts to load from the screw pushing up on the back of the trigger. Continue slowly turning the screw until the hammer falls. Then back off NO LESS than 1/2 of a turn.
    Now it is time for the over travel screw adjustment. With the hammer cocked screw the over travel in until it is just touching the trigger. Now squeeze the trigger. The hammer cannot fall due to the screw being too far in With the trigger depressed start backing the over travel screw out until the hammer falls. Add another 1/4 turn. Cycle the hammer, and test the trigger for release.

    With the hammer in the fired position remove the trigger pin and install the disconnecter. Once installed, with the trigger depressed, cycle the hammer until the disconnector catches. Test for function. If the hammer is captured by the disconnector and releases without dropping the hammer move on to the next step. If you can’t push the hammer past the disconnector or the disconnecter captures the hammer and will not release it your disconnector will need to be “timed.” This is normal as I have never had one function without timing it.
    Timing the disconnector is a pain, once again go slow, and test fit often. With the disconnector on a flat work surface file the spur and pay attention to try and keep the original angle. Only remove a tiny amount at a time. When you file the correct amount from the sear spur the hammer will catch on the disconnector AND release when the trigger is reset. As mentioned, you will get really good at removing and replacing the FCG.

    It is important to do these tests. With the hammer in the upright or fired position pull the trigger and hold it. Now cycle the hammer to the rear. It should catch on the disconnector. Now very slowly release the trigger. The hammer should fall a short distance to the trigger sear or catch. If the hammer bounces off or goes past the trigger and fires you have a very bad situation! This is called doubling and is very dangerous. (Doubling problems are due to the disconnector not engaging properly. Notes at the end of section for repair. ) Pull trigger, hammer should release. Now cycle the hammer without holding the trigger, it should catch on the trigger. Pull and hold the trigger and cycle the hammer make sure it catches on the disconnector again. Repeat this again and again. The process to repair a disconnector only works about half the time. To repair it all you have to do is file about .020” off the pad that rest on top of the trigger. See arrow on following photo.
    If it won’t catch, file here.
    sear.jpg


    Once all adjustments have been made and the fire control passes the function test it is time to disassemble the FCG and use thread locker on both travel set screws. Let it sit over night.


    Part 5) Fitting the safety. The next day, reassemble the FCG take a look through the safety hole. You will notice that the back end of the trigger is blocking the safety from fitting. To rectify this you must remove just enough to allow the safety to function.
    I have found the best (safest) way to get this to work is try the fitting with the hammer removed and the trigger pin removed so that the trigger is just laying in the receiver. Try fitting the safety and then slide the trigger under the safety into position. If you can set the trigger pin and the safety works you are done. If it will not fit, lightly file the back end of the trigger until you can get it to fit under the safety and insert the pin. This will take several tries to get it to fit. Take your time, if you remove too much the safety will not block the trigger. The only way to fix that is by replacing the trigger.

    Finished fitting to the safety
    triggermod.jpg


    The last item you need to attend to is the grip screw, using your cut off saw, remove enough so that it will not contact the pre travel set screw. Now put everything back together, do a safety and function check. If it passes you are done. The pull should be right around 3 lbs, with a crisp break, almost no "creep" and very little over travel.
    Range testing! IMPORTANT SAFETY CHECKS!
    Load one round into the chamber, magazine out. Take aim, slowly pull trigger and keep it depressed. After the shot has fired slowly release the trigger. Listen for the hammer to reset. If the hammer falls, you must repair the disconnector. If the hammer resets, pull the trigger again (click). Do this test 5 times before using a magazine. Then load magazine with 2 rounds only. For this test, KEEP RIFE POINTED DOWN RANGE! Chamber a round and same as above, slowly pull trigger, and slowly release the trigger. Trigger reset and then pull and fire second shot. Do this at least 5 times, if you get no malfunctions your are good to go. Enjoy your new target trigger.
    Hurley's Gold
     

    fast john

    New Member
    Rating - 0%
    0   0   0
    Jul 5, 2017
    1
    1
    Austin
    hi
    Was looking at your DIY ar trigger job and can not see the pictures. Is there something i'm not doing right? New to this site
     
    Every Day Man
    Tyrant

    Support

    Forum statistics

    Threads
    116,119
    Messages
    2,953,344
    Members
    34,941
    Latest member
    Irowland1994
    Top Bottom