In the lower part of the barrel casing is the ejector tube through which the empty cartridge cases are ejected from the gun. The tube is fitted with a spring, which prevents the cases falling backwards into the gun.
The breech casing consists of two outside plates, a bottom plate which is riveted to them, and the rear cross piece, the whole being closed by a cover.
The outside plates are dovetailed into the barrel casing, and, together with the cover, are secured by means of a cover joint pin.
On the outside of the right hand plate there are the following fittings:—(1) a socket and stud for securing and supporting the buffer spring; (2) the resistance piece, and (3) the stud for the check lever. On the outside of the left hand plate are three studs for holding the fusee spring box, the rear one being on the slide mentioned below; there are also two other studs on this plate for fixing a shoulder piece to the gun if required. In both plates are slots partly closed by slides, in which the crank bearings move, and on the inside of both plates are solid cams which control the path of the extractor. Below these, and supporting the side plates, are rests, along which the recoiling portion travels.
Along the bottom plate lies the trigger bar, and underneath is a bracket to which the elevating gear is attached by means of the elevating joint pin.
The outside plates are connected at the rear end by the rear cross piece, into which they both dovetail; this piece is fitted with (1) hollow handles, which are also used for carrying oil, and are closed by milled heads, fitted with camel-hair brushes; (2) a firing lever and spring, the lower end of which fits into the trigger bar, while the upper end is provided with a double button for firing; (3) an automatic double-handed safety catch, which is so arranged that unless it is held up the firing lever cannot be pressed forward; and (4) a pivoted shutter, which, when moved to the right or left, uncovers an aperture through which (when the lock is removed and the crank handle vertical) the barrel can be inspected or cleaned from the rear.
The cover is fitted with (1) springs to ensure the extractor dropping on recoil; (2) a gunmetal block to keep the lock down when back, and (3) at the rear end, a lock to fasten it. On the upper surface is the tangent sight, consisting of a stem, a graduated plate and slide. Running through the centre of the slide is a pinion, the teeth of which work in the rack on the stem. A pawl is secured to the pinion by a fixing pin. On the under side of one end of the pawl are teeth, which engage in the circular rack on the slide.
When the slide is at rest the stud on the inside of the milled head (nearest the slot for the slide spring) bears on the stud on the pawl immediately over the teeth, being actuated by the slide spring, thus forcing the teeth into the circular rack. This keeps the slide stationary on the stem. On rotating the milled head, this stud is partly disengaged from the stud on the pawl, thus permitting a second stud on the milled head to press on one side of the V-shaped ramp at the other end of the pawl. This action releases the teeth sufficiently to permit the pawl being moved round the circular rack by the action of the stud bearing on one side of the V-shaped ramp on the pawl; this moves the slide along the stem. On releasing the milled head, the spring positions the cover, thus causing the stud on the pawl to become once more engaged with the stud on the milled head and force the teeth into the rack.
Recoiling Portion.
The recoiling portion (which is mounted inside the non-recoiling portion) consists of a barrel and two side plates which carry the lock and the crank.