When first model 1857s were cast in Northern foundries they had two handles or "dolphins". After 1861 the dolphins were eliminated, the barrel was shortened from the French version, and it was made lighter. Like most cannons in use at the time, they were muzzleloading weapons. The Model 1857 12-pounder Napoleon with its bronze barrel made up 40% of the cannons on both sides. The U.S. version of the Napoleon could hit a target up to away. However they were most accurate at closer ranges of about . It used a charge of of black powder. The M1857 Napoleon fired a cannonball or canister shot at a speed of 1,440 feet per second (or 439 meters per second). The barrel had a bore of in diameter and was long. The barrel alone weighed . With its gun carriage it weighed and was pulled by a team of six horses. The average gun crew was six men.