Civil War cannonballs are fascinating pieces of history and valuable memorabilia for collectors. Unfortunately, because of the inconsistencies in manufacturing of artillery and the inherent difficulty of identifying a metal orb, it can be difficult to say definitively if your cannonball is really from the Civil War. In spite of this difficulty, look for several tell-tale signs indicating whether your cannonball is a piece of history.
Identify the metal composition of your ball. Civil War cannonballs were manufactured from cast-iron and, on very rare occasions, lead. Other metals like steel, brass and copper, while common in modern artillery, were not used during the Civil War.
Weigh the ball. Compare the weight of the ball to a weight-to-volume chart for cast-iron. The Civil War method of casting always left tell-tale air pockets inside of finished steel shot pieces, so authentic Civil War shot is always slightly lighter than its volume would indicate.
Identify the casting pattern of the ball. Authentic Civil War cannonballs will have three distinct mold markers. The most obvious will be a faint ring around the ball, the mold seam, where the two hemispheres of the casting mold met. The second mold mark will be a circular mark somewhere along the seam. This mark is from the filler hole spruce. The last mark will be a circular casting hole 90 degrees from the mold seam.
Match the diameter of the ball to Ordnance Manual shot tables. These tables were the common standard for cannon shot made during the Civil War, and all shot was manufactured to meet this standard.