My interpretation of the link is pretty much the same as Puffer's.
If not directly intended as a "anti-armored" ball, it seems it would have served the purpose quite well.
I recall reading somewhere that one of the famous Elephant Hunters of that forgone era had special "round-balls" made up with an iron or steel Pyramid shaped object covered with pure lead into a round ball, and shot from a 8 bore, if memory serves me right
Bigsmoke may know more of this than myself, since he's the really big-bore fan.
I do know that wood was once used, and even the Whitworth had a similar configuration for their long range rifle...and the entire theory behind all this experimentation was simply to increase penetration, so why not a Cannon Ball too?
Interesting link, thanks Puff.
Uncle Russ...