barrel and breechblock remain in-line. In the Browning Hi-Power and Colt's M1911 pistol, the barrel is tilted slightly to release it from interlocking ribs, so in this respect, it may be likened to a tilting breechblock, even though it is the barrel and not the breechblock that tilts. This type of floating configuration and recoil operation is not confined to pistols and may be found in machine guns and auto-firing cannons. Interrupted screw Perhaps a variation on the rotating bolt, an interrupted screw provides greater strength than simple lugs while requiring only a partial rotation to release the breechblock. The Welin breechblock is such a design and is used on weapons with calibres from about 4 inches up to 16 inches or more. The Ross rifle Mk III is a straight-pull design that has multi-thread locking lugs. Falling screwed breechblock The Ferguson rifle used a tapered screw plug inserted perpendicular to the axis of the barrel. It was charged with ball and powder and required only one rotation to permit loading. While novel and effective, cost was a factor for its limited acceptance. See also :Category:Firearm actions Notes References External links Breech Mechanisms in artillery Firearm components Firearm actions