I have a 617 no dash that I've done a bit of tuning on. It's had a noticable improvement in the DA trigger and a really noticable change in the SA trigger pull. Actually too much change in the SA pull and I'll fix that when I feel like going back into the lockwork.
What I did was stone the rebound slide, did a bit of light smoothing of the frame where the rebound slide runs with 600 grit wet sandpaper, and install a Wolff 12 lbs. rebound spring. I also put a small dab of RIG grease on the rebound slide to provide a bit more lubrication than a light oil. Since I won't be using this gun in cold weather, using grease isn't a problem, however I wouldn't recomend doing this in any revolver that will be used below about 45 degrees. DA trigger pull is about 8 lbs. and quite smooth. However, that 12 lbs. rebound spring dropped the SA pull to about 1 3/4 lbs, which is light enough that I've become VERY careful to not engage the trigger with my finger until it's sighted on target. At some point I'll install a 14 lbs. rebound spring that will take the SA pull to just a bit over 3 lbs. That will increase the DA pull to about 9 lbs. but it's a tradeoff I can live with, as it is now the SA trigger is just too light to use the gun to train a new shooter.
As for ignition, due to concerns with that I've left the standard mainspring in place and have the strain screw run down tight. My experience with the 617 is that I only start to get misfires when the cylinder gets crudded up by carbon fouling and it becomes difficult to seat the rounds in the chambers. When the cylinder is clean enough that the rounds drop in freely, I've never had one single misfire. I believe that most of the misfires with the 22 are really caused by rounds that are standing off just a bit from the rim in the cylinder, not problems with the ammo or the gun. It's why I now take a brush and boresnake to the range with me, by running a dry brush through the chamber every 50 rounds, I can keep it clean enough that it doesn't get tight during loading.
Bottomline, it's not any more difficult to do an action tuning on the 617 than it is for any other K frame. All it takes is paying attention to details and not trying to lighten the DA trigger too much. It's also not the least bit difficult to do, however for any first timer I would caution that it's much easier to remove material than it is to put it back, so take it slow in stages and stop as soon as you start to see enough improvement. I'll also tell you that getting the DA trigger pull much below 8 lbs. with the 617 just isn't going to happen, if you try you'll just end up with misfires when shooting double action. However a DA trigger that is smooth as butter in the 8 to 9 lbs. range is very doable and reliable.
You'll also need the Kuhnhausen shop manual as a guide for action tuning and a rebound spring tool, both of which are available from Brownells. At the same time you order those, you should also order some lighter rebound springs. For rebound springs, I would suggest the 12 lbs., 13 lbs., and 14 lbs. rebound springs so that you can experiment and see which one you like best.
BTW, the 12 lbs. spring will require that you take the time to smooth any roughness on the frame where the rebound slide runs, otherwise you may experience a failure of the trigger to reset. When that happens it will jam the lockwork up solid until you remember to push the trigger forward. You may also have to work the hammer back and forth a bit to get the rebound slide to free up. BTW, been there done that, only it was with my 610 which now carries a 14 lbs. rebound spring.
If you don't want a sub 2 lbs SA trigger, I would suggest going straight to the 14 lbs. rebound spring, it's functioned flawlessly in all of my revolvers and a 3 lbs. SA trigger is still pretty easy to shoot with. With that spring the DA pull will run about 8.5 to 9 lbs. and if the action is running smooth, it's easy to shoot well with.
BTW, one final tip, keep your fired cases. They can be used as snap caps provided that you put an undimpled area of the rim at the point the firing pin contacts. Unloading and rotating the fired cases really doesn't work well as snap caps but it will allow you do do a funtion test without any risk of harm to the gun. Just remember to only hit the undimpled area of the rim, repeat strikes on a dimpled case permits the hammer to hit the frame and could eventually lead to a broken hammer spur or other damage. Once you hear the difference between hitting a dimpled and undimpled area on the case, you'll understand what I'm talking about.
PS, concerning the file mark on your frame, you can clean that up with a bit of wet sanding using 600 grit sandpaper, however I don't think it's worth bothering with on a shooter. As for the marks on the face of your cylinder, whithout knowing what your End Shake and Barrel/Cylinder gap measurements are, I'm not going to give any advice. Any material removed from the face of the cylinder to smooth out those marks will increase the B/C gap. In your case, it may be wiser to just let a layer of carbon build up on the face of the cylinder to hide the marks.
