This Remington manufactured breech block is for the No. 6 falling block rimfire rifle and is in very good condition exhibiting a grayish brown patina with light wear. The firing pin hole will measure .300" below the top of the standing breech.  (file photo)

Note: No. 6 falling block rimfire rifles with the following calibers and serial numbers have been observed with this part:

22 Rimfire: S143712, J169309, 406768 & 426677