The K, L, and N frames all use basically the same lockwork. While there are some minor differences due to cylinder capacity, in funtion they are basically identical.
If you find the DA trigger a bit gritty, that is an issue that will resolve itself with use, or by dry firing the gun. I recently did some action work on a newer 610 and 620 and what I found was that the only thing required was a change in the rebound spring and a drop of oil on the rebound slide. Normally, the DA sear on the trigger needs to be polished during an action tuning but I found that the range use and dry fire practice that I had done with these guns prior to opening them up had already polished the bearing surface on the DA sear on the trigger.
Bottomline, don't worry about that gritty DA pull, it will clear up in 300 or 400 DA trigger pulls. If that isn't good enough, pick up the shop manual from Brownell's and do a little action tuning yourself, it's not at all difficult and only takes 15 or 20 minutes once you develop a "feel" for getting the sideplate nested in.
BTW, features present in the newer lockwork that used to have to be added during and action tuning. Add a chamfer to the DA sear lever on the hammer, this is already present on the newer guns. Add a chamfer to the one corner on the rebound slide to reduce corner drag, this area is radiused on the newer guns. Stone the 2 bearing surfaces on the rebound slide, the newer rebound slides have a superb surface finish.
About the only surface that may need attention is the DA sear on the trigger, that does have a slightly rough surface on a brand new part. As noted, this surface self polishes with use, so simply using the gun will take care of that surface. However, if you want to touch it up yourself, I would recomend using a 1000 grit stone and using a very light touch to just smooth the surface a bit without removing any significant amount of material or altering it's shape.
If you want to lighten the trigger pull a bit, I would recomend a rebound spring no lighter than 14 lbs. I'll also tell you to purchase the special tool for installing the rebound spring, frankly I don't think it's possible to install the rebound slide without this tool. I tried a 12 lbs rebound spring in my 610 and while it functioned perfectly during dry fire function tests, the trigger failed to reset twice in 48 rounds of live fire practice. Obviously, the recoil during live fire had some effect on the rebound slide returning properly, so going to light on this spring isn't the best choice.
BTW, a weaker rebound spring will also reduce the trigger pull in Single Action. I would estimate that with the 12 lbs. spring in place in the 610 the SA trigger pull was reduced to about 2 lbs., with the 14 lbs. spring the SA pull is probably between 2.5 and 3 lbs.
It is from the 1950's when they really knew how to build things.I hope my other guns wear in a little to feel somewhat like my K38 masterpiece.
