Locking the Barrels to the Frame
In the early models of the breech-loader the barrels were locked to the frame with a bolt operated by a lever placed under the fore end. All modern guns have the top-lever action. In this device a “lump” is fastened to the under side of the barrels near the breech, forming a hinged joint to which the fore end is attached when fitting the barrel and stock together. When closed, the breech end of the barrels is held down to the action and tight up against the breech by a slide, or bolt, which fits into the “lump” attached underneath the barrels. Different makers use various forms of top-lever bolting devices, as the “hook rib” or “extension rib,” otherwise known as the “doll’s head,” and the cross bolt first used by Greener, the celebrated English gun builder. All of these devices are satisfactory on a good grade of gun, but the strongest mechanism is an American invention, known as the Smith rotary bolt. This rotary bolt is tapered and is pushed through an opening in the rib by means of a strong spring. Mechanically this locking device is all that can be desired, and it cannot loosen through manipulation, because of its compensating feature, that is, the spring forces the bolt farther in as the bearings become worn through much service. Many of our well-known builders use this splendid fastening.