Model 1855 rifle-muskets are described in depth on pages 252-259 of George D. Moller's book "American Military Shoulder Arms Volume III", with this exact rifle photographed on page 252 and 253 under the description for the Type I variation. The Model 1855 rifle-muskets were the first U.S. martial weapons manufactured for use with .58 caliber Minie bullets and were widely used during the Civil War. Only 59,273 were manufactured c. 1857-1861. The Model 1861 later replaced the Model 1855 due to the Maynard primer's added expense and unreliability in rough conditions. Dated "1858" on the lock and barrel tang with the standard front sight/bayonet lug, early long range style rear sight graduated 1-4 on the base and 5-8 on the ladder, all iron fittings aside from the brass forend cap, standard lock and barrel proof markings, oval "SB" (inspector Samuel Byington) and "JAS" (sub-inspector James A. Schaeffer) cartouches on the left flat, "US" and "15" marked on the buttplate tang, and "W.C.K." (sub-inspector William C. Kirby) stamps by the bolster and between the cartouches on the left flat. Includes a US socket bayonet, leather sling, and brass tipped wood tampion. Provenance: The George Moller Collection