For our purpose, however, we will be concerned with only three types-primary magazines, ready-service magazines, and ready-service stowage.
Primary magazines are designed as ammunition stowage spaces, generally located below the main deck, and insofar as is practical, below the waterline. They are adequately equipped with insulation, ventilation, and sprinkler systems. These spaces must be provided with fittings so that they may be locked securely. Primary magazines accommodate a vessels complete allowance of ammunition for peacetime operation.
Ready-service magazines are spaces physically convenient to the weapons they serve. They provide permanent stowage for part of the ammunition allowance. Normally they are equipped with insulation, ventilation, and ammunition sprinkler systems, and should be secured by locking. The combined capacities of primary and ready-service magazines are normally sufficient to stow the ships allowance for war and emergencies.
Ready-service stowages are those ammunition stowage facilities in the immediate vicinity of the weapon served. They include weather deck lockers, bulwark (gun shield) racks, and 5-inch upper handling rooms. This stowage normally is filled only when the weapon is to be fried. There is little security for ammunition in such stowage, and it provides the least favorable protection from the elements.
All magazines are marked by appropriate label plates showing the compartment number and the types of ammunition to be stowed therein. Insofar as is practical, magazines are designed to hold a single type of ammunition.
The following designations are given for magazines whenever a single-purpose stowage is practical:
Projectile magazines or rooms
Pyrotechnic magazines or lockers
While stowage of a single type of ammunition in individual magazines is desirable, it is not always possible due to space limitations. Where a ships mission requires carrying various types of ammunition, stowage of more than one type in one magazine is acceptable. Current NAVSEASYSCOM instructions authorize certain mixed stowage in magazines that maintain a single-purpose designation.
Authorization of mixed stowage is at the discretion of the operational commander. Such stowage does not include pyrotechnics that have been removed from containers, or fuzes and detonators that are not integral parts of, or assembled within, the ammunition. These items must be stowed according to the current instructions related to the particular items.
Where mixed stowage of ammunition is necessary, precautions should be taken to make sure the various types of ammunition are segregated within the magazine and each type is suitably marked for ready identification. All specific questions concerning stowage requirements should be referred to Ammunition Afloat, NAVSEA OP-4.