Custom Projectile Weapon Ammo problem

You can use A_JumpIfInventory in your Fire States to check the amount of ammo the player has, and make you weapon go to desired states depending on how much ammo they have.

For example:

Fire:

TNT1 A 0 A_JumpIfInventory("AmmoType", 50, "FireType2)

.

.

.

.

.

FireType2:

TNT1 A 0 A_JumpIfInventory("AmmoType", 100, "FireType3)

.

.

......etc

Whilst it didn't completely answer my question it did at least give me the result I wanted.

As for using specific amount of ammo for each fire type, you just use A_TakeInventory instead of letting the weapon decide how much ammo to consume.

If you are firing multiple projectiles at a time, you can set the ammo usage to the amount you want to entire shot to use, and have only the first projectile use ammo.