History:
Gun was NIB, Mitchel (Uberti) 1873 SAA, 4.75" barrel in 45 LC. Gun shot well but had a pronounced cylinder ring. The bolt was not picking up far enough to clear the cylinder at 1/2 cock, so the cylinder was riding the bolt during ejection & reloading. Also, the bolt was dropping as soon as the hammer was pulled back from half-cock to full cock. Hence, a cylinder ring. Time to change the bolt.

I did my homework and here's what happened:
I fitted a new bolt to the gun. Lock up was perfect with zero play. I even got better cyinder-bore alignment than I had before.
I proceeded to time the bolt to the hammer cam, a ittle at a time. I got a full (below the frame) bolt pick-up @ half cock. I was very happy at this point. I then started to shorten the bolt arm to time the bolt drop.
The bolt was dropping at exactly the same time as the hammer was clicking into the full cock position. Everything was perfect except I
was getting cylinder throw-by with fast action.
I changed the hand spring (with a new Wolf) but that did not fix the problem. It certinly didn't hurt, though.
I shortened the bolt arm a little at a time to get the bolt drop just before hammer full cock and that helped a lot, but it will still throw-by with hard & fast action. Also, when I got the bolt timed perfectly, I no longer get as deep a bolt pick-up at 1/2 cock. I am now slightly above flush with the frame. It doesn't ride the cylinder but it's only a couple of thousands away. I think the bolt is soft where I did the filing and as I cycle the action it is being worn a bit. A couple of thousandths seems to make a big difference on the cam and bolt arm. I am thinking along the lines of hardening this bolt before I cycle it anymore, but I feel that I shouldn't have to.
Any advice here is appreciated.