OK, I've been lurking on this thread because I pulled the trigger on an Uberti 1873 "Sporting" rifle in a 20" barrel about a week ago, in 38 Spl/.357 Mag. I'm not a Cowboy Action shooter, but I certainly understand the appeal.
I've owned lots of lever actions, but never any designed prior to 1885. I've been fascinated with the 1860's Henry (I'm referring to the "real" Henry!) toggle link and shell carrier feature.
Of course, while cleaning the barrel, I couldn't resist taking off the side-plates and checking out the linkage. I don't have measurements of antique 1873's, but the gun appears to be true to the original, including the lever locking latch and sliding breech cover. Cool.
At the range, I discovered the gun won't chamber semi-wadcutters, nor cast bullets with driving bands ahead of the crimping groove). I'll have to be content with round-nose cast bullets and any jacketed bullets. And, because of the precise dimensions of the shell carrier block, it absolutely won't chamber over-length cartridges.
I can report I'm very pleased with my purchase. The gun is very accurate, and seems to be functioning well. Because of the heavy octagon barrel....even at 20"....and the much longer receiver, I need to acclimatize myself to a different balance point than later Winchester and Marlin rifles.
But the best part was when I opened the box on the kitchen table. I explained the rifle's history to my wife, especially about the part it played as "The Gun that Won the West." At which point, my gentle Idaho-bred wife picked it up, opened the back door and shouted, "You varmints get away from my water!"
Hmmm.....maybe we should take up this Cowboy Action thing.....