[Gniarf]

Originally Posted by GUInterface

I believe the max for it is 500 bullets

It's 300, including those already loaded in your current weapon.

Originally Posted by GUInterface

Am I correct in assuming it's something to do with this line?

function Ammo_VampGun:OnTake(player)
    if player.Ammo.VampGun < player.s_SubClass.MaxAmmo.VampGun then
            self.TakeFX(player._Entity, self.AmmoAdd)
            GObjects:ToKill(self)
        else
            return false
        end
end

Yes

Originally Posted by GUInterface

I'm not too good at programming, so I'd appreciate it if someone lent me a hand.

replace

if player.Ammo.VampGun < player.s_SubClass.MaxAmmo.VampGun

by

if (player.Ammo.VampGun < player.s_SubClass.MaxAmmo.VampGun) or (player.Ammo.MiniGun < player.s_SubClass.MaxAmmo.MiniGun) or (player.Ammo.Mp18 < player.s_SubClass.MaxAmmo.Mp18) then

note: I don't mind helping, but due to current state of surgery technology (especially anti-rejection treatments) I'm NOT going to lend you my hand.
(Oh but I can fetch you one from the nearby cemetery)