Mark 45 5-inch naval gun

The Mark 45 5-inch naval gun is the U.S. Navy's standard fully automatic 127 mm deck gun for destroyers and cruisers. In the United States-Iran Conflict archive, CENTCOM and Navy photo coverage show USS Milius firing the weapon during Operation Epic Fury in the Indian Ocean, confirming it as a deployed surface-fire system rather than a legacy mount kept only for ceremonial use.

United States-Iran ConflictUnited States

Conflict side: United States
Built by: BAE Systems
Built in: United States

Mark 45 5-inch naval gun, Naval gun, Artillery

Profile

Type: Naval gun
Conflict side: United States
Origin: United States
Service note: 1971-present

navalsurface fire supportdestroyerguided-missile destroyer

Service History

In service: In U.S. Navy service since 1971; the Mod 4 remains in service aboard destroyers and cruisers.
Used by: United States Navy
Wars: United States-Iran Conflict

Production History

Designer: United States Navy
Designed: 1960s
Built by: BAE Systems
Built in: United States
Produced: 1971-present
Variants: Mark 45 Mod 4

Specifications

Caliber: 5 in (127 mm)
Barrel length: 62 calibers on the Mod 4
Rate of fire: 16-20 rounds per minute
Range: 13 nautical miles with conventional ammunition
Magazine capacity: 600 rounds conventional on destroyers
Weight: 53,770 lb (24,389 kg)

Conflict Usage

United States-Iran Conflict: Side: United StatesRole: Naval live-fire operationsprecision fires
Fired by USS Milius during Operation Epic Fury in the United States-Iran Conflict; CENTCOM listed the destroyer conducting a Mark 45 5-inch light-weight gun live-fire while operating in the Indian Ocean.

Mark 45 5-inch naval gun Images

Mark 45 5-inch naval gun, Naval gun, Artillery - view 1

Mark 45 5-inch naval gun, Naval gun, Artillery - view 2

Mark 45 5-inch naval gun, Naval gun, Artillery - view 3

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Sources

MK 45 - 5-inch 54/62 Caliber GunsPublisher: U.S. Navy | Note: Supports Mark 45 background, primary function, and general service characteristics. | Accessed: 2026-06-20 Mk 45 Mod 4 Naval Gun SystemPublisher: BAE Systems | Note: Supports Mark 45 Mod 4 manufacturer context and the 62-caliber 5-inch gun family in U.S. Navy service. | Accessed: 2026-06-20 Mk 45 Mod 4 datasheetPublisher: BAE Systems | Note: Supports Mark 45 Mod 4 weight and mount characteristics. | Accessed: 2026-06-20 Operation Epic Fury: USS Milius Mark 45 live-firePublisher: U.S. Central Command | Note: Fired by USS Milius during Operation Epic Fury in the United States-Iran Conflict; the page lists USS Milius conducting a Mark 45 5-inch light-weight gun live-fire while operating in the Indian Ocean. | Accessed: 2026-06-20 USS Milius Mark 45 live-fire photoPublisher: U.S. Navy | Note: Supports image provenance for the USS Milius Mark 45 live-fire photo. | Accessed: 2026-06-20 USS Milius live-fire photoPublisher: U.S. Navy | Note: Supports image provenance for the later USS Milius live-fire photo. | Accessed: 2026-06-20 USS Milius Philippine Sea live-fire photoPublisher: U.S. Navy | Note: Supports image provenance for the USS Milius Philippine Sea live-fire photo. | Accessed: 2026-06-20