Ya' won did ya???
The U.S. Revolver Co. was one of several trade names used by the Iver Johnson Co. located in Fitchburg, MA. I.J. made both solid frame and top-break revolvers under the U.S. brand, but the latter was a less expensive version of they're regular top-breaks and lacked among other things their famous "hammer the hammer" safey that was the first transfer bar type used by several manufacturers today such as Sturm Ruger.
The top-break's were made from 1910 through approximately 1935, and some 690,000 were made which proves it was popular. Incidentally they were sold exclusively by mail order. When they were new they sold for about $6.00 - I'm not sure what you paid for your's. Anyway don't feel too bad, Colt Single Actions went for $13.00 at the same time.
It is chambered for the .32 S&W cartridge, and ammunition is available. However I wouldn't be in any hurry to shoot one.