So ranged is a slow skill for sure. The cannon is a cool element of ranged.
But with 1 cannonball per steel bar (and something of "this smelts twice as slow", AND what the wiki says is decreased xp per ball...
Why not make it give 2-4 cannonballs per bar? That would be 250ish each if 4 from a bar, and would see more use of the cannon.

Which of course, there would be complaints still of it hitting NPCs, so... Restrict it? At the same time, it does need a use.
If its setup and you die, you do get a free one back I believe.