If you are able to take it ALL apart, then basically check for any burrs and can polish "mating" parts lightly, or just put a bit of 'Lubriplate' what they put on new cam shafts in a rebuilt car engine, this on "moving parts" especially where the hammer notch and sear engage. On the semi autos, this engagement ( smoothness as well as depth) is the determining factor in "trigger pull".............I've seen (and done) as simple as a drop or two of Breakfree CLP, in this same area, and the triggerpull "lightens up"....lube, time and use makes things go smoother , in the long run.....one must remember when you start to swap parts, make changes, proper fitting has to take place....smoothest shooting RST-4 we ever saw was an early 1950 gun, shot THOUSANDS and THOUSANDS of rounds, and NOTHING was ever done to it....tough to do today at the cost of 22 ammo!!