Look at existing weapons that use it. SolarFlare's Revolver is a good example.
Any Zombies ammo compatible weapon, really.
I have no idea what you did and therefore no idea how to go about fixing it.
It depends if they overwrite the onfire method or not.If they don't it's as simple as adding this:$zombie::ammo::Gun[$zombie::ammo::Listcount++] = YourWeaponProjectile;$zombie::ammo::AmmoYourWeaponProjectile = 60;if they do overwrite the onfire method you'll have to add this:AmmoSYSFire(%this,%obj,%slot);To the onfire method, but even then it's not going to be fully supported, e.g. when you run out of ammo instead of hearing a clicking noise, it'll just get removed from your inventory.
Another reference to the code you can use/add at weapons: