I don't use "Ball Bearings" I use "bearings", They look like a shim. If you think about they are a shim . But they also act like a bearing. The big thing is drag, one burr can cause alot of drag, two will double that. The more drag to cut the less power it takes to work it. Trying to get things fitted is sometimes a problem for me, The MIM parts are way easier to get down to a low drag. You don't remove but a very little material to cut drag, no even a .001 of a inch. The stud that the hammer and trigger set on have alot of drag, take your finger and go around the stud base and on the side plate and you will fell the burrs that cause drag. The stud itself is ruff, use the back side of emery cloth and a little polish compound and then feel it , no material removed but the small unseen burr's. But you can feel the differents, then do the inside and the side plate. Then you get into the hammer and trigger, go around the outside edge with a very fine file and then 1500 paper, and you do this by feel and you do it very lite. Take a 1/8" bit and wrap a piece of 1500 with a lite oil on it a do the hole in the hammer and use a 1/16" bit to do the trigger, you do this very lite, just enought to get the burrs out. I going to stop here, but to do a good action job is a slow drawed out thing that 99% don't want to spend the time to do it. I don't know everthing about a Smith & Wesson, I learn something every day. I wish I could shoot better than I can work on them, shot my 32 today and at 25 yards i couldn't get pass 84 points out of a hundred in slow fire.