Blue Book of Gun Values
25-50 USD
Try "American War Library."
50 or so
There is no information or history on a print of the Last Supper which is stamped us-ap co Chicago stk 791.
That particular pistol was made in 1956 -mail me at nmcop@msn.com KC
No published sn data that I know of.
U.S. Pistol Company DID make a 7 shot smoothbore revolver, but it was not a starter pistol (blank gun). It fired live .22 ammunition.Do not confuse w/ US Revolver Co. (1910-1935) which was a trade name of Iver Johnson's.US Pistol Co was an entirely different firm and was owned by Otis A. Smith. The company was out of the gun business by 1899 (switching to tools) The guns were designed for low pressure Black Powder cartridges only.
You will need to take it to a gunsmith to find out for sure.
Not enough information to even make a guess. You told us the maker- how about caliber, model, condition?
look for a copy of the Blue Book of Gun Values
Roughly 1930s. You may have a caliber .38 S&W, which is NOT a .38 Special.