I'm not an artillery expert by any means, But I do not think that you have a cannonball there, #1 it's not round,#2 It has a flat spot on two sides, (top & bottom, or two sides), the best thing to do ,would be to get EXACT measurements of the object, (Diameter) and EXACT weight. then post it over on the Whats it forum......Cannonballguy will cruise through and answer all your Questions......jmho.................................HH