First off, I am not a gunsmith. Not even close. So please understand that what you read here is not expert advice, but simply one gun owner’s personal experience working on his own guns as a hobby. Before you do any work on a firearm you need to make sure you know what you’re doing – or at least be confident enough to give it a try knowing you may have to replace a part if you screw up. It is possible to damage a firearm if you are not careful.
A quick bit of context/history. I have been a gun owner since I bought my first gun, and Sig P229 back in the late 1990′s. I love that gun by the way. However, my first step into the AR-15 platform was a Colt 6920 that I bought just about two years ago. I really enjoyed how it felt compared to the Romanian SAR-1 AK-47 I had for years. It was more accurate, had less felt recoil and no awful trigger slap.
As I became more familiar with the AR platform and did more reading I became interested in the Sig 516 with it’s pushrod design. I had been very happy with my Sig 229 pistol for 15 years and expected a very well refined piece of hardware with the 516. With my first trip to the range I was very pleased with the rifle. It was accurate and great to shoot, with one exception – the trigger. The feel of the trigger was a bothersome grittiness that could actually be heard. It was a little disappointing. After all, this was not a cheap rifle, and I expected perfection.
A few weeks later the Newtown, CT shooting happened and I decided I wanted to get a couple more ARs (before it was “too late.”) I ordered two more 516′s 48 hours after the shooting. When they came their triggers had that same gritty feel, but were great otherwise. I began looking around the internet for other reports of similar gritty trigger issues on ARs and in particular the 516. I came across Youtube videos like these:
Again, I’m not an experienced gunsmith at all. I am just a guy who has guns and wants them to feel good when I shoot them. I want reliability, consistently, accuracy and smoothness. I made up my mind to take care of my own guns using techniques others shared on Youtube. Once I decided to polish the trigger myself I had to make a list of things required to do the job. I did not use any stones or sandpaper during my polishing.
The estimated time to do this job the for the first time is 45 minutes. By my 4th one it took about 20-30 minutes.
Here’s a list of the things you will need:
- A Dremmel type of rotary tool. I used a Kawasaki Rotary Tool (it’s probably possible, in theory, to do this by hand but it will take MUCH longer)
- Some soft cloth polishing pads/wheels (For better control I used the small cylindrical pad used by “Yankey4″, not the wider thinner one used in the “bassfishingfrenzy” video)
- Polishing compound (I was very happy with Flitz Metal Polish)
- Goggles (there will be debris, mostly polishing compound, hitting your face)
- A Punch (to push out pins during dis-assembly and also to help reassemble the trigger group)
- A small hammer (may be needed to tap the hammer and trigger pins back in during re-assembly)
- Gun cleaning solvent and oil
- Paper towels
- Vice is optional (I didn’t use one even though I had one at my disposal)
The process began by finding the right polishing compound. There are lots of options. You can use the stuff that comes with your tool (not recommended, I tried.) You can use Mothers or Flitz. Since most guys seem to prefer Flitz, that’s what I went with. For about $9 you can get a tube that is probably enough to do about 100 of these trigger jobs, maybe more.
Once I got the compound I had everything I needed and was ready to go. I watched the Youtube videos a couple of times and then headed downstairs to the basement to start working.
First things first. Always safety check your firearm before working on it. Remove the magazine and check the chamber. Then remove the upper receiver/barrel and set it aside.
Then use a punch to push out the hammer spring. Be careful! It is under spring tension so try to hold it in place so it doesn’t take off when you push the pin out. Remove the hammer then push out the trigger pin. Don’t lose your pins and if they are not identical, remember their location and orientation for reassembly. Set the pins aside.
Next, while not required, it is recommended that you remove the hammer and trigger springs so they don’t get in the way during polishing, and don’t get compound/debris on them. Just remember the orientation of the springs for reassembly. Note that in some Youtube videos they may remove the disconnector spring. It’s up to you. I did 4 trigger jobs and never once removed that spring and had no issues. Set all pins and springs and the disconnector aside so they won’t get any polishing compound or other mess on them.
You will now need to wipe all oil and dirt off of the hammer and trigger. You may use a dry paper towel or use a little solvent. Just remember that you will have to clean it again after you polish, so don’t waste a lot of time getting these parts squeaky clean during this step. Just make sure you can polish the contact points without having grime in the way.
At this point if you prefer to use a vice you may carefully secure your part in the vice. I didn’t bother with my vice and had no difficulty at all.
Get your dremmel plugged in and install the soft cloth polishing wheel and apply a modest amount of Flitz. You don’t want to put on so much that it gets flung off by the rotation when you turn on the tool. Also apply a small amount to your contact surfaces of the hammer and trigger. The hammer has two tiny areas to polish. That notch/lip where the trigger catches, and the “chin” just below it that rides/rotates along the top of trigger when the trigger is pulled and the hammer rotates. The trigger has two larger surfaces to polish. One is a nearly square area on the front of the trigger that sits in that notch on the hammer and the other is the top of the trigger that will be contacted by the hammer as it rotates after the trigger is pulled.
Once your polish is applied you should put on your goggles. DO NOT try this without goggles. My goggles were covered with dozens of spots after the job, and you will get stuff on your face and in your eyes without goggles.
Now you are ready to polish the contact points (circled in red above.) Set your Dremmel to a speed somewhere from low to medium, depending on the RPMs it runs at. The faster it goes, the less pressure you should apply against the metal, and the less time you should apply the buffer to the metal. I found the I felt most comfortable doing my first pass at a slower speed. Then I would wipe off the black goo, apply more compound to my polishing wheel and hit it again and a higher speed.
The Hammer: The notched lip on the hammer is a very small but critical part to polish for a nice smooth trigger pull. If you were to just work it at a medium speed I would say the lip on the hammer would require no more than 3-4 minutes of polishing total, with a minimum or pressure, probably about 1lb of pressure maximum. Let the tool do the work and do not press the wheel too hard. You do not want to remove material, round any corners, or change any angles. Then move on to the “chin” below the lip on the hammer. It is not quite as critical to polish and I only hit that with about 1-2 minutes of polishing. That’s it for the hammer.
The Trigger: The trigger will take a little more time because there is a larger surface area to cover there. The square contact face the rests in the hammer lip is a critical surface to polish for a smooth trigger pull. Particularly the 1-2 mm closest to the corner, because that’s really all the ever touches the hammer. (You can demonstrate this for yourself by dry-fitting the trigger and hammer to understand exactly where the contact points are and how they impact the feel of the trigger.) Again, great caution must be taken to ensure you do not round off that corner. That face may require 4-5 total minutes of polishing, depending on the speed setting you choose. Once that area has a mirror finish with nearly no visible machine marks and no texture to your fingernail you are done. (The same could be said for the hammer lip, but it is almost too small to polish that completely.) From there, you may want to polish the larger area above the face. I do not believe that top area matters to the smoothness of your trigger pull, but I polished it anyway to ensure a nice smooth area for the hammer to rotate over. If you’re not sure if you’re done, wipe down the contact points and dry-fit them and simulate the pressure and rotation of the hammer and see how smooth it feels. It should have some mild feel of friction even with a mirror finish on the contact points, but it should be noticeably smoother than before you started. Odds are if you have a mirror finish you are done.
So that’s it for polishing. Take your time. Do it a little at a time. Wipe off the grime and add new Flitz to your polishing wheel every couple of minutes or as needed. Do not run at a high speed and do not apply much pressure at all. You should barely be able to feel the wheel pressing against the parts. This is one benefit of NOT using a vice. You get two hands worth of feedback about the pressure you are applying, and you also get better control of the angles you are using. It is also easier to move a small piece of metal than a large tool.
Next you should do a very thorough job of cleaning all the mess off of your hammer and trigger. Then lightly oil them, and make sure you get a thin film of oil on those contact points, including into the lip. Then wipe away excess oil so it doesn’t interfere with motion or attract new dirt during operation. Light oil on the springs and pins couldn’t hurt as well. If removed, you may now place the springs back onto the hammer and trigger.
Reassembly can be a bitch, I’m not going to lie. First, make sure you have the the safety in the “FIRE” position to allow the trigger to move a little bit more during installation of the hammer. Next get your punch ready. First you want to put the trigger in and set the disconnector on it. Line up the holes by looking for daylight through the holes and the don’t try to insert the pins right away, but instead insert the punch. A punch that is close to the same size as the pin seems to work best for this. The punch is MUCH easier to get through the hole than the pin. So line up the holes and push that punch in (from the right/starboard side) to hold everything in place. Then you can push your pin in from the left/port side and use it to shove that punch back out as the pin goes in. Repeat this technique for the hammer pin. Just make sure the holes are lined up. You may need to ever so gently tap on the pin with a small hammer to get it into the holes, even when properly aligned. The hammer is a pain to install because the spring can be rather difficult to compress with one hand while you hold the punch with the other hand. Be patient and use a punch. Going for it with the pin right away will end up frustrating the hell out of you.
Now you should be looking at a lower receiver with a complete trigger group installed. It’s time to function check the trigger and safety using your finger or some other soft yet resilient object to catch the hammer before it slams into the frame and hurts itself. You will have to test the trigger about 5-10 times before it starts to feel really smooth. It takes a few cycles of the trigger to seat properly and work the lube out of the way I guess. By the 10th or 15th pull if it’s not smooth you may want to take another look at it. I found that by the 5-10th pull it was nearly frictionless, with the only sensation being the pressure of the trigger against my finger. There was no hint of grittiness at all, just a steady, smooth pressure until a sudden “SNAP” as the trigger breaks. I did 3 Sigs and a Colt this way and the all feel exactly the same now. If satisfied, reassemble the upper receiver and you’re done.
I hope you find this information helpful. I want to thank those guys who posted the videos that gave me the courage to attempt this on my own. Prior to this I had never taken apart an AR trigger and wasn’t even 100% clear on exactly how it worked. Now I know precisely how my trigger works and I have a sense of pride that I have done something for these guns myself. I just don’t understand why they wouldn’t do this at the factory. I guess time is money, but this seems like a really cheap, quick and simple way to make the gun feel WAY better to the shooter.
Let me know what you think.