The caches are wooden crates with Brotherhood of Steel insignia on them, containing the powerful Hellstorm missile launchers. They fell out of the Brotherhood First Expeditionary Force's possession during the fight with raiders that killed Knight Alan Connors, and have since spread to several parties in Appalachia.
- One BOS weapons cache is retrieved at the end of Disarming Discovery, in the throne room at Dagger's Den. It is removed from the player character's inventory upon returning it to Fort Atlas.
- Another can be acquired at the end of Supplying Demands. It is in the possession of Mike Tiller at Kerwood Mine, though he does not want to give it up. If he is convinced to let the player character take back the weapons themselves, the cache can be taken from a nearby steamer trunk. What happens to the cache afterwards depends on how the player character deals with the following confrontation at the Foundation supply room.