Finished it up, finally.
First, the cylinder lock. There was enough rotational play to figure I'd best replace the lock before moving on to the hand. First I narrowed the bit that actually fits the cylinder slots so it would fit the narrowest one. That still left me with 0.004" more metal than the old lock. Then I made sure it fit the frame slot without binding. That took another 0.001" off, and I polished the sides, very slightly beveling the top where it first touches the cylinder slot and polishing the top so it rides along the cylinder smoothly.
This is where it got interesting, because that cylinder lock does several things. There's an edge that has to be lapped so that the lock isn't withdrawn all the way inside the frame or it could stick down and disable the revolver. And the ramp leading to that edge is the one the finger at the front of the trigger rides up push the lock forward to ratchet itself back into place for the next trigger pull. The new part was made with enough material that it was all just a process of removing the right amount rather than having to add any, and this got figured out and adjusted.
Last was the hand. I did use Diekem and found where it was binding. It was a pretty large area, so I borrowed a whetstone and went at it, thinning it another thousandth. Then I polished that face with the hard Arkansas so it was smooth and flat. Lots of messy hand work doing that. Several more fits and tries to make sure I'd gotten to where it wasn't binding. Near the end, only two chambers were still binding the hand and only in single action, and I think that was because of the slight differences in the lugs that the hand engages. I pulled it apart, polished a little more, got a tiny pick and cleaned out the pawl window, put it back together and dry-fired double and single action until I knew that in this perfectly clean state everything works as it should.
To make sure I hadn't screwed up the chamber alignment (shouldn't - the worst it even could be was the amount removed from the lock thickness and that effectively puts it back where the factory made it) I slid some drill rod down the barrel. Not really a good test as the throats are the same diameter as the grooves, but I did it anyway. Then I used an LED pea bulb against the firing pin bushing and looked down the bore and everything seemed to line up as well as my eyeball can tell.
So I've been snapping and grinning and feel pretty good about this. The cylinder locks up with no play at all at full cock and with the trigger pulled. There's still a teensy bit of play when it's all at rest, but noticeably less than before. Feels like a
new old Smith & Wesson. I do still have to take it to the range and wring it out completely though.
And I saved a couple hundred dollars and learned a whole lot!
-Don