Some form of peace-bond, perhaps? A large amount of cash/valuables deposited with the local constabulary as a guarantee/leverage against any frivolous use of weapons heavier than those used to settle "gentlemen's disputes".
Or perhaps a more physical form of "peace bond", as in a thin but strong chain tightly wound around the cocking handle/charging lever/bolt/trigger and then padlocked. You would be able to unwrap the weapon in a few moments and then load it, but you couldn't just squeeze off a few rounds in anger.