Ammunition is generally of two types: separate loading and semi-fixed. Semi-fixed ammunition (rounds) appear in the traditional form of a projectile mated with a powder canister. The canister is outfitted with a primer which fires upon contact from the firing pin. Powder and projectile are separate from each other until they reach the cannon. Powder will be shipped in bulk (usually on a palet). Projectiles and primers are likewise shipped in bulk. Separate loading ammo is just that: the projectile is rammed home in the chamber, the powder bag(s) is loaded (usually by hand) and the primer is inserted into its interstice when the breech has been secured. All normal projectiles arrive at the weapon with a plug in the fuze well. The decision as to which type fuse to use is made by the fire direction center and carried out by the gun crew.