: A place for storing the accessories and accouterments of war.
In professional settings (military, police, or correctional), "proper" text typically refers to standard operating procedures (SOPs) or safety guidelines:
: Specifically a storehouse for powder and ammunition . Operational and Safety Procedures
: Historically, a place where arms are manufactured or stored. In modern US usage, it often refers to a National Guard headquarters where equipment is kept and training occurs.