This factory manufactured lock plate sub assembly - left side is for the American Gun Company hammer double shotgun in 12 and 16 gauge and is in very good condition exhibiting a grayish brown patina with light wear.  This lock plate sub assembly is complete less the hammer and hammer screw  (file photo)

Note: American Gun company shotguns with the following serial numbers have been observed with this part:

12 gauge: 253579 & 332253

16 gauge: 216299