An Armory.
What I would most likely do is go to the closest store that sells both weapons and ammunition along with food and medical supplies, defend the building with your life.
An arsenal, a weapons cache, etc. Armoury
Ammunition shelf's were where the soldiers kept their ammunition and guns.
A secret weapons store is often referred to as an "armory" or "weapons cache." In military and covert operations contexts, it may also be called a "weapons depot" or "munitions storage facility." These locations are typically discreet and designed to store weapons and ammunition securely.
Weapons are kept in Armouries. Ammunition is kept in a magazine. They should not, never ever, be stored together.
Weapons, armor and ammunition.
Weapons and ammunition are stored in an armory, magazine, silo, arsenal or at a weapons or ammo dump. In a home they should be stored in a secure safe or chamber/trigger locked with ammunition locked up separately.
A storage place for weapons and ammunition is commonly referred to as an armory. An armory can be a facility used by military or law enforcement organizations to store their weapons and related equipment securely. In civilian contexts, similar storage facilities may also be called gun safes or gun lockers, depending on their design and purpose.
Put trigger locks on the weaponsTrain your kids to safely handle weaponsSecure your ammunition and empty your weapons
Arsenal or armory.
Some examples of military weapons and ammunition include rifles, pistols, machine guns, grenades, missiles, and artillery shells.
heavy weapon Ammunition fired in artillery weapons such as cannons, howitzers and mortars.