Staff Writer (Updated: 2/8/2013):
As a percussion-based firearm, the Model 1855 utilized "percussion caps" for their required ignition of the primer powder. Prior to the invention of percussion-based firearms, operators utilized the "flintlock" ignition system which was an improvement over the previous "matchlock" and "wheellock" developments but was itself limited by damp weather conditions which led to misfiring. The percussion-based arrangement now protected the primer from exposure to the elements and proved a much more sound and reliable ignition system. Since percussion-based guns could still be actuated through a "cocking" arm (now operating as a true "hammer" rather than an arm designed to hold a piece of flint rock) many flintlock guns could be converted to percussion-based firearms as time, money and motivation allowed.
The percussion-based system relied on its hammer hitting a percussion cap set upon a nipple, the resulting action igniting the primer powder within the weapon. The cap was applied by the operator to the weapon prior to firing and was generally of a small cylindrical shape manufactured of brass or copper - capped at one end and managing a small supply of "explosive" at the other. Once the operator had loaded his weapon and the percussion cap was in place, he need only cock the hammer and press the trigger to release the hammer against the awaiting percussion cap. The resulting ignition of the primer powder then drove the "ball" bullet from the barrel through simple pressure and force. The percussion-based system is still applicable today, though primarily recognized in its slightly evolved form as "cap guns". The percussion cap was adopted around 1820.
The Model 1855's external arrangement and appearance were consisted with musket designs of the time (musket defining its muzzle-loaded requirement). The weapon managed a full-length wooden stock with embedded metal components that made up the critical firing function. The stock was of a smooth dark walnut finish with a slightly ergonomic butt with a basic integral hand grip. The curved trigger assembly was protected within an oblong trigger ring under the firing mechanism which was itself offset to the right side of the body in the usual way concerning flintlock firearms. The mechanism was primarily dominated by the hinged cocking arm and fixed percussion nipple. The Model 1855 made use of the "Maynard Tape Priming" magazine system, a development attributed to Edward Maynard which involved percussion caps set about a strip to help ease and speed up reloading of percussion weapons (the Model 1855 was the first American-produced long gun to use this), as oppose to management of individual caps fumbled out of a pouch. The Model 1855 was chambered for the expanding-base .58 caliber "Minie" ball bullet - the first standard-issue American Army long gun to do so. Iron sights were fitted over the main area of the gun body (a folding leaf graduated out to 900 yards) as well as just aft of the muzzle (as iron block). The Model 1855 musket managed another "first" in this area as the first American long gun to feature a rear sight for ranging targets at long distance (beginning in late 1858, the folding rear leaf was replaced with a simplified two-leaf assembly). Due to the weapon's overall length, the standard 40-inch barrel was mated into the long-running stock with three barrel bands for rigidity. Her musket origins required loading from the muzzle-end of the barrel and this was aided by a long iron ramrod sheathed in a sleeve under the barrel. The process of reloading a musket (whether flintlock- or percussion-based) still proved time-consuming when compared to breech-loaded rifles. A bayonet could be fitted under the muzzle in the usual way, its mounting secured by way of the front block sight.
Harpers Ferry also produced a shortened carbine form of the Model 1855 with a 33-inch long barrel which required only two barrel bands about her stock resulting in a more compact form. However, production of this series was severely limited to about 7,600 units before the facility was captured by Confederate forces during the war. The armory was set alight on April 18th, 1861 by an outnumbered and retreating band of Union troops in hopes of rendering the production equipment useless. However, local residents - many whose livelihood depended on the armory - managed to control the spread of flames which spared much of the equipment. Short of all types of war-making arms due to a general lack of an industrial base in the South, Confederate forces claimed the equipment and shipped the booty off to safer territory for manufacture of muskets for the rebel cause. As such, the Model 1855 became one of those storied weapons to have fought for both sides of the grand and bloody American conflict.
Despite her impressive production numbers, few Model 1855s survive in excellent-to-good condition today, making them prized collector's items fetching several thousands of dollars.