I guess I haven't done the best job describing this. In many--if not most--of the Uberti revolvers I've received or examined, the timing at full cock of the hammer is off. In my experience, most commonly the hammer reaches full cock before the cylinder has fully rotated into position. Functionally, it still works, as further rearward cocking of the hammer finishes rotating the cylinder, but this late carry-up is wrong, self-worsening over time, and difficult for me to correct. Sometimes I've been able to stretch the hand successfully, though as you know, sometimes lengthening the hand to correct this also causes the cylinder to begin its rotation too soon, before the bolt has dropped all the way out of the notch. Very difficult for me to fix on a single-toothed hand, which is why I prefer the two stage hand.
Everything is interrelated.
On my friend's revolver, the hammer reached full cock precisely when the bolt locked into the cylinder notch. I was very pleased when I saw this, because so few Uberti revolvers I've handled did this. But when placed on halfcock, the bolt was allowed to rise up through the water table enough to rub on the cylinder. When one first starts cocking the revolver, the bolt disappears into the frame, but the half cock position is a notch on the hammer, so when you reach half cock, the hammer moves forward again slightly, and this lowers the bolt tail a little and allowed the bolt head to start protruding slightly through the water table. As you know, there is a lot less room between the cylinder and the frame on these open top designs than in the SAA, and it doesn't take much movement of the bolt to make a big difference. Also, the cylinder stop notches are more shallow.
So I don't know exactly what Uberti got wrong on this revolver. At hammer rest, the bolt tail sits just on top of the cam lobe and begins to move the moment the hammer starts to move back on cocking--just like it should. So it doesn't look like the cam is mis-positioned or shaped. And the tail drops off the cam when it should, positioning the bolt head about midway in the cylinder stop notch leades. Timing-wise, everything appeared to be on the money, except that the bolt head rose too far during half-cock, and it rubbed on the cylinder. The new bolt I fit was the same, and I took no metal off the bolt leg. It drops when it should, and it moves the moment the hammer starts to cock. BUT, it, too, rose too far during half-cock and rubbed on the cylinder. All this leads me to believe that Uberti got the sear or hammer notches wrong but managed to time everything anyway, ignoring the fact that the bolt was now rubbing on the cylinder at half-cock. So I had to dress the bolt down until it no longer contacted the cylinder during half-cock. There is still plenty of protrusion into the cylinder notches after the bolt leg falls off the hammer cam, so I think I'm good there. I could take a little metal off the ledge on the bolt nose if I need it to rise further, but then I'd have to take some metal off the bottom of the bolt tail to compensate, since it is already resting on the cam as is. And for all I know, that might have a neutral effect, because a thinner bolt tail will cause the bolt head to rise higher during half-cock, and I'd be back to dressing down the bolt head again. No free lunch.
So right now, the bolt fitting has gone well, and the revolver behaves as one perfectly timed. Even the chambers are lined up well with the ejection rod and gate at half cock. But it took so long to accomplish dressing down of the bolt, because one can't really see the bolt working on these open top designs, as it is hidden by the curve of the water table. And I didn't want to take off too much metal and have it fail to lock the cylinder when it should, so this became one of those "fit-n-try" marathons. I bet the action was disassembled and reassembled 25 times. The cylinder was spun by hand so many times to try and discover exactly where it was rubbing and by how much, that there is now a bolt turn line on the cylinder completely devoid of finish. And some finish has been rubbed off of the roll engraving where the cylinder was inexplicably touching the water table there as well. And all of this disassembly, reassembly, and cylinder rotation evidently was enough to wear the gas ring portion of the cylinder into its corresponding seat in the barrel assembly enough to develop endshake again and close the cylinder gap completely. And that necessitated facing the barrel breech back a little to achieve some barrel cylinder gap again. So when I get done re-lapping the barrel assembly back a little to eliminate the endshake again, I fear I'll run out of wedge. So I'm now seriously considering your mod., despite some misgivings. My short arbor fix uses the Dillon locating button (ala Pettifogger), and that is much easier for me to adjust incrementaly by just chucking the tail into the drill press and dressing it will files, stones, and sandpaper. With your mod, I'm going to have to switch to washers. It is straightforward enough, but I haven't done it before, and I don't like learning on my friend's revolver. He ponied up the cash for the new bolt and chocked that up to really inexpensive action work, since the bolt cost $27.00. But if I mess up this adjustable wedge mod, I'll have more or less ruined his revolver. Right now, it functions well, and I think the average Joe would like it as is, but my friend wanted a smooth-cocking but tight revolver, and right now, with that endshake having developed again, it just isn't tight.