Cornell publications might have what you are looking for.
Try Hopkins & Allen. Depending on condition, anywhere from $25-100.
Inexpensive turn of the century handgun
25-100 USD or so
Best bet is to look at old gun catalogs in a library.
Take it to a gunsmith.
BLue book of Gun values
Probably an assembly number.
10-100 USD or so
0-150 USD or so
Hopkins & Allen Arms Co. Fifty Years of Gunmaking 1867 - 1917 by Joseph T. Vorisek is about the best book on H&A.