The AK Short Throw Trigger; A Tutorial By Gunfixr
We all know that the AK fire control group is rather crude, although rugged, and its trigger pull is somewhat less than glamorous. It's long and creepy, and kind of clunky. First, for those not sure about doing this, Red Star Arms sells a trigger all loaded up with set screws that will do the same thing. It's about $85. Personally, I don't trust the screws for something like this, as they can move later. If they back off, no big deal. If they close up, the gun could stop working. I have no personal experience with this set, so I don't know if they actually do or not. I'm just cheap, so I figured a way around it. Plus, the welds won't change, once you set it, it's good for life. For this episode, I used a Tapco G2 single hook FCG, and it's being fitted into a Saiga S12 shotgun. Any AK, with any AK FCG, will be pretty much the same, except for a full auto setup. I haven't done one of those yet, but it'll be forthcoming. So, on to it.
In the first pic, is the factory Tapco parts. The only parts that are modified are the trigger and the disconnector.
In this pic are the same parts after welding. This can be done however you want, be it TIG, Mig, stick, whatever. You want a small bubble on the edges where the trigger makes contact with the inside of the receiver, both front and rear. For a double hook, there would be a bubble under both hooks. Realistically, a bubble could only be put on one side of the rear, but I like balance. It lessens the likelihood of the trigger skewing around any on the slop of the axis pin, which will increase friction. The bubbles on the trigger are about 3/32" to 1/8" tall.
The one on the disconnector is about 1/16" tall. I eyeball it. You can cut down the sides of the bubbles flush to the trigger if you want, it's not necessary. I do, because it looks better, and makes a neater pad when I'm done.
Ok, now for the fitting. The tip of the hook on the trigger has a small flat on the end where it comes down to close to a point, This is where the hammer slips from underneath when you pull the trigger. This flat is not cut square to the trigger, but is actually a bit of an overhang. As you pull the trigger, it will break from under the end, and hit this overhang, and push it out of the way as it clears. On a normal setup, this is no big deal. For the travel to be seriously shortened, this needs to change, or it wastes space.
So, take a file and taper it a bit the other way. I still leave a very small flat there, just angle back most of it. It doesn't need to be a real steep angle, just enough to make the hammer be clear of the hook once it breaks the bottom of this flat, instead of riding up the overhang. Standard AK FCGs may or may not have this same issue. Check it and see. Some of the FGS, notably the Maadi, have a real high square type hook, and the hammer lobe will ride this as well. The top part of it would have to be clearanced also.
Now to begin fitting. Start by installing the trigger and hammer in the receiver, on their pins. With a Tapco trigger, include the slave pin sleeve. Do not install any springs. You should not have to remove the hammer for the whole operation. You may find that the trigger pin won't go all the way in because the trigger won't set down low enough due to the welds. This is not uncommon. Start by filing down the front bubble, the one on the trigger hook. File a little and test, stop once you get the trigger pin in. The hammer should not go past the hook at this point. If it does, and it clears by more than a tiny amount, reweld and start over.
Next, you need to get the hammer past the hook. So, you take a look at by how much the hammer is shy of clearing the hook, remove the trigger, and file some. If you're not sure, it is always better to file not enough than to file too much. File and check, file and check. If you're going slow enough, you'll reach a point where the hammer will go by, but you can feel it bump the tip of the trigger hook as it does. File just a bit more. You want the hammer to miss the hook by just enough that it will always go by, even if a little dirty, but not by a large amount. A word of caution here. While doing this checking, make sure the hammer and trigger pins are fully seated, as if they move out a bit, and the pin gets to the retainer groove, it will mess up your location, and give you a false clearance reading. (I missed a pic here,oops, but I think you understand)
You are done with the front of the trigger at this point. Now, to set the hook catch distance. This is the amount that the hook actually holds the hammer by. This is done by filing down the bubbles on the rear end of the trigger. Again, file and check. How much you set this to is entirely up to you. The pic shows what I like best. It's enough that even on a 12ga, it always works, but is short enough that bump firing is quite easy. The more hook overhang, the longer your trigger pull will be, the less, the shorter. Personally, I wouldn't go much shorter than pictured, but it's your choice.
When filing, at first just try to keep them kinda level with each other, they don't have to be perfect. As you get close to done, you want to try to keep them the same height, I check them with calipers. I'm not looking for a specific height, just that they are the same. Caliper jaws are parallel. This keeps the trigger from skewing when released. If you rock the trigger back and forth, until it stops at each end, you will now see what your length of travel is. You are now done with the trigger.
Now to make the disconnector work. First, go ahead and file down the bubble on the disconnector, and only leave about 1/32" behind. You need very little on this part. Taper the end so that the contact point will be right at the end, as shown. Install the disconnector, with its spring, into the trigger, and the trigger into the receiver. It may not even catch the hammer, when the hammer is lowered into the trigger/disconnector, and the trigger pulled back. That's ok. Start filing down what's left of the bubble on the disconnector, going a little at a time and reinstalling to check. What you're looking for is for the maximum amount of disconnector hook catching, but still clearing the hammer when the trigger is rocked forward, as if releasing. You want the disconnector to clear the hammer fully, with just enough gap to be sure to release the hammer, even if dirty. Note: Tapco parts are cast, and have a seam. If you smooth down the seam on the disconnector hook and the hammer lobe, you can cut this space very close.
Disconnector hooked:
Minimal clearance:
Here is what the parts look like after being welded and fitted.
You will have to refit the safety. It shouldn't engage at all, as the rear end of the trigger is sitting somewhat higher than it was. With the safety against the trigger, look and see where it needs to be relieved, remove it and file down the blade of the safety. Once again, file and check, going slowly. This is really important, as slop here is dangerous. Remember, you just made the trigger movement to fire really short. You cannot have a lot of play, where the trigger will move before hitting the safety and stop. You want the least amount of movement of the trigger you can get, without the safety binding against the trigger as it goes by. You're done at this point. Check function by fully assembling the FCG in the rifle, reassembly of the rest of the rifle, and hand function check. Pull the bolt back and let it go. Engage the safety. Pull the trigger, it shouldn't drop the hammer. Disengage the safety. Pull the trigger, the hammer should fall. Holding the trigger to the rear, pull the bolt back and release. Release the trigger, you should hear a "click", and feel the reset. Pull the trigger once again, the hammer should fall. The springs do not need modification, you will find that the trigger seems quite light as is.
It should be again fire tested at the range, to be sure that the recoil and parts moving quickly don't have any adverse effects not noticed when hand cycling. One final note: you can stone/polish the engagement surfaces if you like. It'll make the pull feel even lighter, and smooth. Just don't round the corners, as the small engagement areas could lead to improper operation, such as accidental firings, double/triple taps, etc. Enjoy!
