 The boxlock action uses concealed, self-cocking hammers in a break-open action.Strongly opposed by most sportsmen and manufacturers at first, the boxlock action quickly became the dominant form of double-barreled shotgun action.The boxlock action was the result of a long evolution of hammerless actions, created by two gunsmiths, Anson and Deeley, working for the Westley-Richards company in 1875.