This Springfield Armory manufactured late variation hammer with the fine cross hatch checkering in an oval panel on the thumb piece is for the later model 1873 trapdoor rifle and carbines and is in very good condition exhibiting a brownish gray patina with some traces of original blue finish along with a few specks of rust.  (file photo)

Note: Late variation hammers will be found on firearms with serial numbers above circa 86,000.

Note: U.S. Springfield Armory trapdoor rifles with the following serial numbers have been observed with this part: 130964