Fig. 30.
The Block, [Fig. 30], is threaded for a distance of four inches from its forward end, and the circumference of the thread is divided into six equal parts. The threads of the block are removed along three alternate sectors, as is usual in the interrupted-screw fermature, to allow the block to slide in the corresponding slotted sectors in the jacket (or base-ring in earlier model).
The threaded sectors engage in the corresponding slotted sectors in the breech-block, but one sixth of a turn of the block will engage the screw-threads of both.
The interior of the block is bored out to form the obturator-spindle recess.
At the end of the block are two lugs for the lever-handle. On the right one is a shoulder which limits the motion of the lever-handle.
The Nose is the front end of the block, slightly reduced in diameter in order to partly enter the gas-check seat.
The Stop-groove, into which the stop on the carrier-ring enters, is in the planed sector on the left-hand side.
Fig. 31.