Well darn, I actually measured the cylinder gap and it is .02.
If I am reading your post correctly, that is a .020"gap? If so, I'll defer to Goon or Hawg.
First, that it a
very nice looking replica London 1851 Navy 2nd Model Squareback, and fairly accurate to the original as the load-lever pivot screw enters from the right side and the cylinder stop-slots are rectangular. I have always been fond of the looks of a SB TG but not the silver plated TG and backstrap. The loading aperture on the barrel lug appears to be correct as well as the lever latch and catch, and it has no recoil shield cap groove (Swayze). The wood is nice but what's up with the diamond?
I understand that the arbor is short, but if the wedge is tapped in until wedge spring protrudes on the right side of the barrel you should have little or no gap. If you do have that huge gap, the wedge is too wide on the cylinder side and pulling the barrel away from the cylinder.
If that is the case, I would buy a spare Uberti wedge and experiment with sanding down that side of the wedge until it is a thumb-press fit, and then cold blue it. I have done that with all of my Pietta 1851 Navy type pistols but the Pietta arbors are not short. You might have to fit the arbor length to the barrel lug arbor hole first.
I am just a rank newbie here and I would solicit advice from some of the better informed members if I was you.
Good luck with your endeavor, sir.
Regards.
Jim