This Springfield Armory manufactured seventh variation breech block with the low arch is stamped "U.S. / Model / 1884" and is for the model 1873 trapdoor rifle and carbine. This breech block is in very good condition exhibiting a mixture of applied hot immersion blue finish with a brown patina and having a few specks of older rust and/or pin prick pitting.  (file photo)

Note: Trapdoor rifles and carbines manufactured between December 1886 through June 1893 and having serial numbers circa 360,000 through the end of production would have been manufactured with the seventh variation breech block.