And tell how are you going to trow 100 5mm to somoene? seems a bit hard if you ask me.
You should try to play Arcanum by one of perverted character-builds:
Half-ogre with max. STR and throwing skill.
Pick up any item and start to throw at anyone you see. Btw, this is the funniest of builds I've ever played, especially when you throw plated armors or shields or even steam engine or automaton-droid at someone! Also there's imbalanced thing. You can find huge stone in one quest which you can pick up only with almost max. STR, and... you can throw it on 1 square only, but it has really huge weight and does like 9999 damage and kills anyone, so this is one of the strongest builds in Arcanum (of couse don't count imba mages)!
Now to topic:
This can be useful, btw throwing 100 5mm is possible, don't forget this is box with ammo, not 100 bullets laying in your pocket.
It can work like in JA2, depends on item's weight, but 2/3 AP is too low, it must have the same AP as throwing grenade.
And don't create "T" button or something, just make possible to pick item from inventory, then close inventory and lay this item on any hex, and then character will throw this item there (or atleast at this direction, if it's too far). You can thow any item, but armors/rockets/bazookas/minigus will be thrown on 1-2 hexes depening on your STR, while light weight items like grenades.
But I don't think it's worth it, to implement it.