NO. 3 20 GRAIN IGNITING PRIMER
A. Body, obturating-cup, vent-closing disc, primer charge, end-closing wad. (See No. 2, Fig. 97.)
Note.—The following data is given for general information only:
Weight of the piece, 1722 pounds. Length, 154·5 inches. Length of bore, 50 calibers. Number of grooves, 24. Twist of rifling, 1 in 50 calibers at the breech and increasing to 1 in 25 at the muzzle. Kind of powder, smokeless. Weight of charge, 5 pounds. Weight of projectile, 15 pounds. Muzzle velocity, 2600 feet per second. Muzzle energy, 702·9 foot-tons. Penetration in steel, at the muzzle 5·37 inches; at 1000 yards, 3·82 inches; at 2000 yards, 2·72 inches; at 3000 yards, 1·94 inches.
Q. Point out the following parts of the breech-block:
Block.
Carrier plate.
Carrier plate ring.
Locking spring.
Lever handle.
Threaded sectors.
Slotted sectors.
Extractor.
Firing pin.
A. See Figs. 17 and 19.
Q. What acts as the gas check?