How were US Civil War cannon balls made?

Answer 1

Cannon balls were usually called solid shot, or round shot, during the Civil War. There were many types of ammunition for artillery. Round shot were used on ships, to smash through the sides of enemy ships, and also against forts, to smash down walls, but were not the favorite type to use against enemy troops. Shells, bombs, shrapnel or "carcasses" were preferred against enemy infantry, until they got close, then the preferred load was canister, case or grape shot. The first types were all hollow projectiles filled with explosive and some type of metal pieces, such as rifle balls, that would scatter when the shell was exploded by a fuse. The second type were all projectiles filled with many small balls, which made the cannon like a giant shotgun, and were very devastating against enemy infantry at close range. The most common types of ammunition carried with the artillery operating with the armies were shells, and canister or case shot.

Cannon balls, and the smaller balls filling a canister or a case shot, or a bag of grape shot, were all made of cast iron. The molten iron was "cast" into a mold, usually a sand mold. After cooling the ball was removed, and the seam around the middle where the two halves of the mold met had to be filed off, along with the sprues where the hot iron was poured into the mold, and the vent sprue which allowed the air to come out of the mold as the liquid iron poured in, and let the caster see that the mold was full.

See the related links below for a more detailed explanation of types of ammunition and the manufacturing process.

These generalities all hold true for the most common type of cannon used by both sides, a 12 pound "napoleon". They were called "12 pounders" because the balls weighed 12 pounds; the guns themselves weighed about a ton, and could be made of iron, or infrequently brass or bronze. There were other types of cannon in use, including some types of rifled guns, which had grooves inside the barrel to make the ball spin. This made rifled guns much more accurate than the smooth bore (no grooves) 12 pounders. Some of these rifled guns required special ammunition, molded to fit snugly into the grooves in the barrel. Armstrong and Whitworth guns were common types of rifled guns. Much bigger guns could be used on ships, which were so heavy that if used on land they would sink into soft ground and get stuck. Dahlgren and Parrot guns were huge cannon used on ships, some of which fired 300 pound balls. Sometimes massive mortars were used to bombard forts, from ships, or if used on land they were fired from railroad flatcars or from specially constructed, heavy-duty platforms. These mortars fired huge projectiles at a high angle, to get over the walls of a fort and explode inside.

Answer 2

Cannonballs were either iron or steel. Some had lots of lead or steel shot, a sort of shotgun shell.