Between 1842 and 1855, Eli Whitney Jr. received five contracts from the U.S. War Department to manufacture newly adopted U.S. M1841 percussion rifle: 7,500 in October, 1842 (delivered between 1844 and 1847); 7,500 in March, 1848, subsequently extended to 10,000 in January, 1849 (delivered between 1849 and 1853) 5,000 (previously contracted for by Edward K. Tryon) in October, 1848 (delivered contiguous with 1848 contract for 10,000); 5,000 in 1853 (delivered between 1853 and 1855); and 100 in 1855 (delivered that year). All except the final 1,100 delivered in 1855 conformed to the model made at Harpers Ferry, and of those 1,100, the only difference of 500 of them was the ramrod. This rifle was 49" in length overall, having a 33" long browned barrel, with .54-caliber rifled (7-groove) bore. Barrel bears stamp of inspection at the breech, usually "U S /(inspectors' initials) / P", while the left flat (after mid-1848 for Whitney rifles) should also bear stamping "STEEL" to indicate the barrel had been rolled from "cast steel". Furniture is brass, buttplate bearing stamped letters "U S". Lockplate is flat with a beveled edge and bears horizontal two line inscription "E. WHITNEY" / "U S" forward of the hammer and vertical two line inscription "N. HAVEN" / (date) on the tail. (Date also appears on breech plug tang). As originally made, M1841 rifle was not adapted for a bayonet, though several modifications were made to the rifle between 1855 and 1862 to affect that adaptation.