1 BBs description in Pip Boy
As for now it is
"A package of BB's from before the war. In excellent condition. Stainless steel."
and it is crafted out of
4 junk 
Maybe the description could be something like
"A package of BB's made from metal and metal like junk"
2. lower 9mm ball crafting requirements
as for now it is 1 metal part and 4 gunpowder... which is pretty much for the worst weapon except BB gun
It would be nice if 9mm ball would be made of 1 metal part and 3 or 2 gunpowders. Why? Maybe then somebody would really use it. You get tons of that ammo from encounters while it is not needed then because simply its too shitty to win against such encounters (marauders if Im correct) Maybe some really low level encounter viable to be killed by mauser would also do the trick