I recently acquired a US Revolver Co. (made by Iver Johnson) top break revolver. The caliber is .32 Smith and Wesson which was originally a black powder cartridge. This means that modern smokeless powder .32 caliber round will not work in this gun. They will fit but it is a more powerful load and most likely destroy the gun if fired. The loads are extremely difficult to come by, we will hand load them. 
Iver Johnson was a U.S. firearms, bicycle, and motorcycle manufacturer from 1871 to 1993. The U.S. Revolver Co. was an offspring and set up as a mail order only company to rid themselves of the Second Model frames when the Third Model (designed for smokeless powder) frames came out. They were of the same quality and had the same pricing as the Iver Johnson models. Iver Johnson's have been known to be of lesser quality than their Smith and Wesson cousins but the values on the S&W's are well out of my price range.
This gun particular gun was manufactured between 1910 and 1923 but we have not ascertained the actual age because the serial number is under the grips. The grips are mother-of-pearl, which are very fragile. We could easily break them if we tried to remove them so we have not attempted to do so.
I have wanted a break top revolver for quite a while. Many years, in fact. Why? Because its neat! Most revolvers you see the cylinder will either be fixed or swing out. In a top-break revolver, the frame is hinged at the bottom front of the cylinder. Releasing the lock and pushing the barrel down exposes the rear face of the cylinder, which also extracts the cartridges.
The condition of the gun is remarkable considering it's age and its difficult to find them at reasonable price in such good condition. A pretty cool little gun, but I don't know how much I'll be shooting it.
”A free people ought to be armed.”
~George Washington