1884 trapdoor carbine stampings

[rjb223]

Carbine buttplate below U.S. has 92 and below that is 1st Sep. Co. Can anyone identify these stampings or offer some direction to finding out. Thanks, RJB.

[Dan Shapiro]

Here's a possibility:
America's part in the world war: a ... - Google Books (http://books.google.com/books?id=Pf9MAAAAMAAJ&pg=PA600&lpg=PA600&dq=1st+Sep.+Co.&source=bl&ots=QNk2k2cVDi&sig=k34DTir1MtPAjEdXXLfdJXhzVwo&hl=en&ei=5LBLSsz_FYLGMIql-aMB&sa=X&oi=book_result&ct=result&resnum=3)

"92" may just be a rack ID number.