I do like the idea of having something other than building components that trains the siege engineering skill. Maybe using random chunks of rock could still be used for training purposes, but they could have a massive accuracy penalty that effectively makes them useless for actual combat.
I wouldn't get too complicated with the options however. 1 stone could turn into 2 balls or 2 loads of something like grapeshot. The stone could work like normal rocks do now, and the grapeshot could work like throwing a large amount of small stones (and we all know how effective small spinning stones can be!), but it would have a short range.
Of course this should not prevent throwing anything else as catapult ammo. Some sort of tag on the stocks screen that allows you to label something as "catapult ammo", item haulers then take it to a catapult ammo stockpile. If I want to throw my artifact elephant leather thong that is encircled with bands of pumice, let-r-rip!
And, just because I'm a nerd like this, Tolkien clearly states that the men of Minas Tirith did not have catapults large enough to reach the orcish army. Jackson got that part wrong. The whole thing about the heads though, brilliant! You do not want to fight a war against the Witch-King of Angmar!
[ September 14, 2007: Message edited by: Yucca ]
[ September 14, 2007: Message edited by: Yucca ]