The U.S. Army Rifle, Model 1841 was the first percussion-ignition weapon adopted by the U.S. Army. Manufactured with a .54-cal. barrel with seven grooves with one turn in 6 ft., the rifle was designed to fire a 0.535" patched round ball backed by a charge of 75 grains of blackpowder. The 9-lb., 12-oz. Model 1841 had an overall length of 48 1/2", and it had a case-hardened percussion lock stamped with the maker’s name and the date of manufacture. The lacquer-brown, 33" barrel was equipped with a brass blade front sight and a “V”-notch rear sight set for 50 yards. The barrel’s breech was stamped with “V.P.”, an “eagle-head” and date at the breech. The two barrel bands, trigger guard, buttplate and patchbox were made of brass, while the steel ramrod was of the trumpet-head type and had a brass tip. The rifle was originally designed without provision for a bayonet.
With the outbreak of the War with Mexico in 1846, former senator Jefferson Davis was appointed to command the 1st Mississippi Volunteer Infantry Regiment, and used his connections with the War Department to get his regiment equipped with the new percussion rifles. During the battle of Buena Vista, Mexico, in February 1847, Davis' regiment stopped several Mexican cavalry charges cold with concentrated rifle fire from these weapons, and they became famous as the "Mississippi Rifle" based on this incident. Looking through early Confederate weapons and ordnance reports you commonly see references to "Harpers Ferry rifles," "minie rifles," "Whitney rifles," "Palmetto rifles,", etc., nearly all these refer to the M1841 rifle or one of its contractor clones. A vast majority of Confederate-designed and manufactured rifles are based on the M1841 and its follow-on, the M1855, further demonstration of just how popular (and effective) these weapons were.
All U.S Model 1841s were fabricated at the Harpers Ferry Armory, and contracted copies were also made by a number of private contractors, including: Eliphalet Remington, Herkimer, NY; George W Tryon, Philadelphia; Eli Whitney. Jr., New Haven, CT; and the partnerships of Robbins, Kendall & Lawrence and Robbins & Lawrence, Windsor, VT.
Between 1844 and 1855, about 80,000 Model 1841s were delivered to the Ordnance Department. The Palmetto Armory of Columbia, SC, also manufactured a small quantity of M1841 rifles for South Carolina in the early 1850s, and George Tryon sent a number of M1841s to the Republic of Texas in 1844.
The M1841 was replaced by the M1855 rifle, caliber .58 in 1855, and subsequently contracts were let to re-bore the M1841s on hand in the national armories to .58 as well, fit them with long-range rear sights, and fix them so that they could be outfitted with bayonets.
The M1842 was the first percussion ignition smoothbored musket, in caliber .69, and was the last in the long line of .69 smoothbores in Army service. It was produced at both the Springfield and Harpers Ferry armories, with approximately 250,000 turned out between 1843 and 1855, when the Army standardized on .58 caliber rifles and rifle muskets. About this time, some 50,000 of the M1842s were rifled and fitted with rear sights, and some of these saw service during the Civil War.