hmmm. in my experience, separate weapons and ammo need to be taken separately from an ammocrate.
to clarify the context, this is for a script which will summon a stocked ammocrate to the player's position. the ammocrate is script-created. it has very little ammo in it (actually only grenades, hand-grenades, satchels, flares and smoke shells), but if the player doesn't already have a flare or hand-grenade in the inventory, the 'throw' part of the weapon has to be taken first, then the ammo works. simply adding/taking the ammo doesn't.