The technology is truly extraordinary.
I’m curious, when did, what year and what wars, the cannon ball go from a metal ball to something that exploded on impact ?
I don't know. There is this fictional show on Starz, called "Da Vinci's Demons" about a fictional version of young Leonardo Da Vinci. The most recent episode had the Church and Pope worried about an invasion fleet of Turkish ships about to sack a Christian seaport city. So Leo gets the crazy idea to have his friends core the cannon balls to lighten them, then fill them with gunpowder and a wick. So they do all this overnight, load their cannons, light the wick and shortly after fire the cannons. Yeah, right! In real life, it probably took many years of experimentation before it actually worked.
Of course, you're probably don't mean a ball that explodes after landing on a target, but a shell that detonates when it strikes.
Wonder when some hobbyist will create self-guiding ammo that regular folks can make for themselves...