I've been trying to figure out a picture in my head of how this locking system could have looked and worked, if it actually existed. I was wondering rather than a long rod running through all the butt holes locking them to the rack if each individual rifle could have been locked to the rack by way of the butt hole, independently of all the other rifles in the rack? Each rifle would then require some sort of special lock/hasp with it's individual key, presumably.