16"/50 Mark 7 - United States Naval Gun
Originally intended to fire the relatively light 2,240 pound (1,016.0 kg) Mark 5 armor piercing shell, the shell handling system for these guns was redesigned to use the "super-heavy" 2,700 pound (1,224.7 kg) APC Mark 8 before any of the USS Iowa class battleships were laid down. This heavier projectile made these guns nearly the equal in terms of penetration power to the 46 cm (18.1") guns of the Japanese Yamato class battleships yet they weighed less than three-quarters as much.
The weapon is constructed of liner, A tube, jacket, three hoops, two locking rings, tube and liner locking ring, yoke ring and screw box liner. Some components were autofretted. As typical of United States naval weapons built in the 1940s, the bore was chromium plated for longer barrel life. Uses a Welin breech block that opens downwards and is hydraulically operated. The screw box liner and breech plug are segmented with stepped screw threads arranged in fifteen sectors of 24 degrees each.
Gun Characteristics
| Designation | 16"/50 (40.6 cm) Mark 7 |
| Ship Class Used On | Iowa (BB-61) and Montana (BB-67) Classes |
| Date Of Design | 1939 |
| Date In Service | 1943 |
| Gun Weight | 267,904 lbs. (121,519 kg) (including breech)
239,156 lbs. (108,479 kg) (without breech) |
| Gun Length oa | 816 in (20.726 m) (breech face to muzzle) |
| Bore Length | 800 in (20.320 m) |
| Rifling Length | 682.86 in (17.344 m) |
| Grooves | (96) 0.150 in deep (3.81 mm) |
| Lands | N/A |
| Twist | Uniform RH 1 in 25 |
| Chamber Volume | 27,000 in3 (442.5 dm3) |
| Rate Of Fire | 2 rounds per minute |
| Note: The primer cartridge can be either electric or percussion fired. | |
