.69 caliber. 42" barrel. SN: NSN. Bright finish, iron furniture, American Black Walnut stock. Single shot percussion muzzleloading musket upgraded by rifling the bore, with the barrel secured by three flat, spring-retained barrel bands and mounted with a brass blade front sight. Lock marked in three vertical lines at the tail: SPRING/FIELD/1853 and with a {Spread-Winged Eagle}/US forward of the hammer. Breech with V/P/{Eagle Head} proofs and the breech plug tang with a matching 1853 date. No visible cartouche on the counterpane. The musket retains both sling swivels and a full-length iron trumpet head ramrod with threads at the end. While nominally 23,000 or so US Model 1842 muskets were upgraded by rifling and sighting them at Springfield, Harpers Ferry, St. Louis and Frankford Arsenals and are readily apparent by the addition of the long range rear sight, this is one of the less obviously upgraded muskets. The barrel is rifled with three grooves in the traditional US arsenal method, and is one of 20,076 upgraded by rifling between 181857 and 1859. These alterations were performed at the four arsenals listed above and by the Benicia Arsenal as well.