IF you were going to do such a huge addition. Might it not be easier to also rebuild the entire weapons list? Some how make sure all the weapons are represented while still being slightly different (IE why have more than 1 9mm pistol if their stats are identical). I would suggest sorting out your calibers and classifications and adjust where your models sit accordingly. Then if you have similar weapons in the same caliber add specific mods so that each weapons has slightly different functionality. Have each caliber represent by at least one auto pistol, revolver, smg, rifle (single action), rifle (semi auto\auto), Heavy weapon, and maybe something wacky for kicks. This way you don't end up with a ton of cosmetic weapons but you still end up with variety and you don't need so much ammo. Be nice to overhaul the ammo too but that may be intensive.