Dual purpose - climbing protection, placed like a cam or chock, particularly a revolver with the ability to swing the cylinder open. A break top revo could be used as a sort of carabiner. The ultimate master key for opening stubborn locks - mind the shrapnel and the spatter. You could leave a trail of rounds, instead of bread crumbs, to find your way home. ULers would want to use use empty casings - much lighter.