8-inch/55-caliber Mark 71 gun
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The U.S. Navy's Major Caliber Lightweight Gun program was the 8"/55 caliber Mark 71 major caliber lightweight, single-barrel naval gun prototype that was mounted aboard the destroyer USS Hull in 1975 to test the capability of destroyer-sized ships... Wikipedia
Barrel length: 440 inches (11.165 m)
Caliber: 8 in (203 mm)
Crew: 6
Effective firing range: 32,000 yards (29,260 m) at 41° elevation
Feed system: 75 rounds on ready service loader
Rate of fire: 12 rounds per minute (rpm) automatic maximum; Guided projectiles: 6 rpm
Used by: United States Navy