Just any FYI, the "Swamp Angel" fired a 8" 200lb. shell, there were only 36 rounds fired on Charleston from that gun before it "burst"/broke the barrel and was permanently out of commission.This piece you've found, by your pics, looks to small to be the Confederate Brooke ( 2.8 inches dia). The Union fired on Charleston using 20 and 30 pound Parrott shells, and your piece looks like its one of the two. The fuze cavity is not correct for a cannonball. The 20lb is roughly 3.5 inches diameter and the 30lb is a little over 4 inches. You should be able to guesstimate its diameter with proper measuring. Your piece could have been fired from the famous "Swamp Angel" .