
The 12-pounder Whitworth rifle was invented by Sir Joseph Whitworth, and imported into North America during the Civil War. Although the Whitworths are generally associated with the C.S.A.--most were run through the Union blockade--there was one battery in Federal service in 1861. This battery only saw field service during the Peninsula Campaign in 1862, and for the remainder of the War was part of the defenses around Washington, DC. The Whitworth was the only breechloading rifle to be used in the Battle of Gettysburg.On 2 and 3 July, located on Oak Ridge, the Confederates, taking advantage of the Whitworths' superior range, fired them with impunity at the Federal positions on Cemetery and Culp's Hills.
While capable of firing the same types of ammunition as other rifles, the Whitworth rifle was most often loaded with solid "bolts." In the case of the breechblock's jamming, the Whitworth rifle could be loaded from the muzzle. The rate of fire of a breechloader was not significantly greater than than that of muzzle-loading artillery.
Bore Diameter 2.75 in (7 cm) Tube Material Iron and Steel Tube Length 104 in (264 cm) Tube Weight 1,092 lb (495 kg) Powder Charge 1.75 lb (0.79 kg) Range (5° Elevation) 2,800 yd (2,560 m) At Gettysburg 2 (CSA)
http://einstein.human.cornell.edu/ACW/arty/12whitworth.html