The Spindle has a head (g) at the forward end, its surface being plane and its sides conical, with the larger diameter of the cone in front. The vent (c), 0.2 inch in diameter, passes through the axis of the spindle, and the copper bushing (c) is inserted by pressure at the front end.
The Gas-check Ring (f) is nearly triangular in section, coming to a point at the front. It fits accurately on the conical surface of the head of the spindle, and is slightly longer in the direction of the axis of the bore than this head. Its rear surface rests against the front surface of the block, while the rear surface of the head is not in contact with this front surface, and can only be brought in contact with it by a heavy pressure, which will expand the gas-check ring.
The Spring (e) acts against a shoulder in the block and a corresponding shoulder on the obturator-spindle, and tends to press the spindle forward.
The Obturator-nut (d) prevents the action of the spring from forcing the spindle too far forward, and also regulates the tension of the spring.
The spline-screw acts as in the de Bange system. This screw is used in place of the locking-nut (d′) shown in figure.
THE LEVER-HANDLE.
(See [Fig. 37.])
This handle (h) acts as a lever to rotate the block, its head acting as a cam to withdraw the block and obturator when the latter sticks after firing, and to lock the block in the carrier-ring and prevent rotation during firing. It is supported in the lugs (l) of the breech-block by a pin (e) and rotates with the pin; to which it is secured by a screw entering vertically. The head of this pin has a projection (a) which strikes against the corresponding stop on the right lug and limits the motion of the lever-handle.
THE BRONZE-HANDLE.
(See [Fig. 37.])