Have been tinkering with my K22 X-Trim a bit, hopefully take it out soon and see how it's working. The slide to frame fit was already really smooth, nothing to improve there. I did polish the hammer and underside of the slide a bit so the slide moves back over the hammer a little more smoothly. Did a little tuning to the extractor (sharpened it and stretched out the extractor spring). There's not much other tweaking I can think of doing as the overall fit and finish is really good. I think the biggest challenge is the K22 X-Trim slide is pretty heavy @ 270gr. It's a lot of mass to cycle for a .22 round. The K22s slide is only 210gr (measure by tracifan68) which is going to be much easier to cycle.
Did a couple of things to one the mags. The mag spring is a lot stronger than those on mags of my other .22 semi-autos. Doing some rough measurement, they average ~1.5 lbs whereas the K22 spring is ~3 lbs down-force to load the first round. It's a pretty long spring, extends about 2 1/4" below the bottom of the mag. I cut back a coil at a time and measured. Ended up cutting off 4 coils which reduced the down-force to ~2lbs 4oz. Didn't want to reduce it too much more as there is a little stiction in the movement of the mag follower. Will look at that another time. I also tried leaving a mag fully loaded for 24 hours, but so far, it has not changed the spring force.
While I had the mag apart, also fixed the problem loading that 10th round. There's a plastic guide rod attached to the mag floor plate that stops the mag follower - preventing loading more than 10 rounds. Just sanded 1/32" off and now the 10th round loads pretty easy.
One thing I am worried about is the long term durability of the magazine plastic feed lips. Would prefer metal feed lips, but will see how long these last. The good thing is they were pretty cheap @ $16 from Dlask, so I bought a bunch.
Hoping to get out tomorrow and see what impact the changes have.