I want to start by saying that all triggers are all different and do not attempt anything referenced here if you are unsure about how the AK trigger works, or the relationship the parts should have.
Well, I have converted several Saigas (I think I might have done one of the first .308s many years ago) and I have always used G2 triggers except one that I used a RedStar Arms adjustable. The RSA trigger was adjustable for over-travel and pre-travel and was very nice.
So the Saiga I just acquired has a G2 trigger already in it and has the typical long pull with lots of over travel. I started thinking about how to make it better. The first thing I always do is fabricated a shim with a hole that lines up with the rear trigger guard bolt. What this does is shorten pre-travel. I have a certain source of steel on hand with a hole already in it that I have used for years to do this (it just happens to be nearly perfect) and have done it on every Saiga I have owned. The shim just gets the trigger sear closer to the release point on the hammer. RedStar does this with a screw, I do it with a shim that can never move or get loose (bolt for trigger guard gets red locktight). If you have a non-Saiga AK, welding material on the trigger in this area and a trial fit and file work would be one option. An epoxy blob on the receiver filed to fit or a shim epoxied in place would be another.
This is trial and error and I always stop tweaking the shim (or choosing thicker shims) when the hammer just misses the disconnecter with the trigger in the forward-most (released) position. MAKE SURE THE HAMMER MISSES THE DISCONNECTOR when you move it rearward by hand with the trigger all the way forward in it's released position(the hammer will be under the sear). This leaves a very safe sear/hammer relationship but is worlds better in "pull length til hammer release" compared to an unmodified trigger.
Now for the over-travel. RedStar uses a screw to stop the trigger movement rearward after sear release. I do this by adding a little material to the trigger where is comes in contact with the receiver right under the sear. the trigger's movement is stopped when this area contacts the receiver during a trigger pull. I welded a little material to this area on the bottom of the trigger and then filed it down a little at a time (test fitting it multiple times) until the sear/trigger stops right after the hammer is released.
MAKE SURE THE HAMMER DOES NOT TOUCH THE SEAR with the trigger in it's rearmost position (normal trigger finger pressure). wiggle the hammer laterally and make sure there is no contact at all while the trigger is held rearward. Make sure the disconnecter has plenty of bite on the hammer when it is rotated back and the trigger is held rearward(or the weapon may double when fired).
Now, one more thing. You will find that your safety lever will not go all the way back in due to your trigger movement being shortened so much. Grind a small amount off of the safety until it goes back in. The area that blocks the trigger is not touched unless your AK safety will not go into position to block the trigger. In this case, a small amount of material will need to be removed to allow the safety to be fitted to your trigger.
There you have it. An AK trigger with around 5/32” total trigger movement that is safe and reliable. Be sure to test fire and make sure there are no doubles and with the hammer cocked, (unloaded and pointed safely up) strike the butt hard a few times on the ground to make sure the hammer will not release.
This trigger while not bolt gun nice, is certainly semi-auto nice and is just as good as my Bill Springfield done AR trigger. It is very short and the firm stop makes it seem more crisp and solid.
As always, YMMV and if you do not understand how a trigger works and how much engagement it needs to be safe or what the parts relationships should be, do not attempt any trigger work. I provide this for information only. Please be safe. Paul