# 5-inch/54-caliber Mark 16 gun

The 5"/54 caliber Mark 16 gun (spoken "five-inch-fifty-four-caliber") was a late World War II–era naval gun mount used by the United States Navy, and later, the Japan Maritime Self-Defense Force. These guns, designed originally for the Montana-class battleships and then the abortive CL-154-class cruisers, were to be the replacement for the 5"/38 caliber secondary gun batteries then in widespread use with the US Navy.

## Design

The 5"/54 cal gun turrets were similar to the 5"/38 caliber gun mounts in that they were equally adept in an anti-aircraft role and for damaging smaller ships, but differed in that they weighed more, fired heavier rounds of ammunition, and resulted in faster crew fatigue than the 5"/38 cal. guns.
The ammunition storage for the 5"/54 cal. gun was 500 rounds per turret, and the guns could fire at targets nearly 26,000 yards (24,000 m) away at a 45° angle. At an 85° angle, the guns could hit an aerial target at over 50,000 feet (15,000 m).
The cancellations of the Montana-class battleships in 1943 and then the CL-154 class cruisers in 1945 pushed back the first use of the 5"/54 cal guns to their installation aboard the US Navy's Midway-class aircraft carriers. The guns proved adequate for the carrier's air defense, but were gradually phased out of use by the carrier fleet because of their weight (rather than having the carrier defend itself by gunnery the task would be assigned to other surrounding ships within a carrier battle group). These mounts were then installed in the Japanese Akizuki-class and Murasame-class destroyers in 1958–59.

## Usage

| Ship | Gun Installed | Gun Mount |
| USS Montana (BB-67) (cancelled 1943) | Mark 16: 20 × 5"/54 caliber | Mark 41: 10 × twin mount |
| USS Ohio (BB-68) (cancelled 1943) | Mark 16: 20 × 5"/54 caliber | Mark 41: 10 × twin mount |
| USS Maine (BB-69) (cancelled 1943) | Mark 16: 20 × 5"/54 caliber | Mark 41: 10 × twin mount |
| USS New Hampshire (BB-70) (cancelled 1943) | Mark 16: 20 × 5"/54 caliber | Mark 41: 10 × twin mount |
| USS Louisiana (BB-71) (cancelled 1943) | Mark 16: 20 × 5"/54 caliber | Mark 41: 10 × twin mount |
| CL-154-class cruisers (six ships, cancelled 1945) | Mark 16: 12 or 16 × 5"/54 caliber | Mark 41: 6 or 8 × twin mount |
| USS Midway (CV-41) | Mark 16: 18 × 5"/54 caliber (all removed by 1980) | Mark 39: 18 × single mount |
| USS Franklin D. Roosevelt (CV-42) | Mark 16: 18 × 5"/54 caliber (some guns removed before retirement in 1977) | Mark 39: 18 × single mount |
| USS Coral Sea (CV-43) | Mark 16: 14 × 5"/54 caliber (all removed by 1980) | Mark 39: 18 × single mount |
| USS Mississippi (AG-128) | Mark 16: 5"/54 caliber (Unknown quantity–test ship) | Unknown |
| JDS Murasame (DD-107) - Murasame-class destroyer | Mark 16: 3 × 5"/54 caliber | Mark 39: 3 × single mount |
| JDS Yūdachi (DD-108) - Murasame-class destroyer | Mark 16: 3 × 5"/54 caliber | Mark 39: 3 × single mount |
| JDS Harusame (DD-109) - Murasame-class destroyer | Mark 16: 3 × 5"/54 caliber | Mark 39: 3 × single mount |
| JDS Akizuki (DD-161) - Akizuki-class destroyer | Mark 16: 3 × 5"/54 caliber | Mark 39: 3 × single mount |
| JDS Teruzuki (DD-162) - Akizuki-class destroyer | Mark 16: 3 × 5"/54 caliber | Mark 39: 3 × single mount |