Artillery

Mark 45 5-inch naval gun

Also known as
  • Mk 45
  • Mk 45 5-inch gun
  • 5-inch Mk 45 gun
  • 5-inch/54 caliber Mark 45 gun
  • 5-inch/62 caliber Mark 45 Mod 4
  • 127mm Mk 45
  • 127 mm/54 Mark 45
  • 127mm/54 Mark 45
  • 127 mm/62 Mark 45 Mod 4
  • 127mm/62 Mark 45 Mod 4
  • 5-inch 62-caliber Mk 45 Mod 4 Naval Gun System
  • Mk 45 Mod 4
  • Mark 45 Mod 4

The Mark 45 5-inch naval gun is a U.S.-origin, fully automatic 127 mm shipboard gun mount used on destroyers and cruisers against surface, air, and naval surface fire-support targets. Sourced combat use includes USS Carney firing Mk 45 illumination rounds during the 2016 Sirte campaign, Red Sea counter-UAV gunfire by U.S. destroyers, and 2026 blockade enforcement.

Mark 45 5-inch naval gun, Naval gun, Artillery
Image source: USS Milius Mark 45 live-fire photo

Role in Conflicts

2023 Red Sea Crisis
Air Defense

Used from U.S. Navy destroyers during the 2023 Red Sea Crisis; USNI News reported USS Stockdale sailors shooting down a Houthi UAV with the ship's five-inch gun, and the Navy's Carney account describes the destroyer's main 5-inch gun firing during the Oct. 19, 2023 Houthi missile-and-UAV engagement.

Role details
2016 U.S. Campaign Against ISIS in Libya
Fire Support
Side
United States and Libyan Government of National Accord

USS Carney supported Operation Odyssey Lightning near Sirte; USNI News reported that Carney fired illumination rounds from the destroyer's MK 45 5-inch lightweight gun while supporting strikes against Islamic State targets.

Profile / Specs

Profile

Origin
United States
Built by
BAE Systems
Type
Naval gun
Service note
1971-present
Designer
United States Navy
Designed
1960s
Produced
1971-present

Specifications

Caliber
5 in (127 mm)
Barrel length
54 calibers on Mod 1/2; 62 calibers on Mod 4
Rate of fire
16-20 rounds per minute
Range
13 nautical miles with conventional ammunition; more than 20 nautical miles for Mod 4 with Navy 5-inch Cargo projectile and improved propelling charge
Ready loader
20 conventional rounds in the automatic loader drum
Magazine capacity
600 rounds conventional on destroyers; 1,200 rounds conventional on cruisers
Normal firing control
Remotely fired from the Mk 160 Gun Computer System or Mk 86 Gun Fire Control System
Weight
53,770 lb (24,389 kg)
Variants

The Mark 45 family spans earlier 5-inch/54 mounts and the longer-barrel 5-inch/62 Mod 4. U.S. Navy material ties the Mod 0 deployment date to 1971, and BAE Systems says existing Mod 0-2 mounts can be upgraded to the Mod 4 configuration.

VariantConfigurationDesignation notes
Mark 45 Mod 0Original 5-inch/54 lightweight gun mount

The U.S. Navy fact file lists 1971 as the deployment date for the Mark 45 Mod 0.

Sources: MK 45 - 5-inch 54/62 Caliber Guns

Mark 45 Mod 1/25-inch/54 shipboard mount

The Navy fact file groups the 54-caliber Mark 45 Mod 1/2 barrel at 270 inches, while RAND identifies many DDG 51 hulls as hosting the Mod 2 variant.

Sources: MK 45 - 5-inch 54/62 Caliber Guns, RAND Naval Surface Fire Support Assessment

Mark 45 Mod 45-inch/62 upgraded naval gun mount

BAE Systems identifies the Mod 4 with a 62-caliber barrel, strengthened subsystems, advanced control-system enhancements, a reduced-signature gun shield, and forward-fit use from DDG 81 onward.

Sources: Mk 45 Mod 4 Naval Gun System

Ship Classes And Mounting Context

The Mark 45 is a shipboard gun mount rather than a stand-alone land artillery piece; its cataloged context is strongest where sources connect it to DDG 51-class destroyers.

CarrierCarrier typeCarriage evidence
Arleigh Burke-class guided-missile destroyer, Guided-missile destroyer, Naval SystemsArleigh Burke-class guided-missile destroyerGuided-missile destroyer class

The DDG 51 fact file lists a five-inch gun in Arleigh Burke-class armament, BAE Systems says Mk 45 Mod 4 is forward-fit from DDG 81 onward, and RAND states that each DDG 51 hull accommodates one Mk 45 mount.

Sources: Destroyers (DDG 51), Mk 45 Mod 4 Naval Gun System, RAND Naval Surface Fire Support Assessment

Mount, Magazine, And Upgrade Context

The Mk 45 is a shipboard gun mount whose main distinctions are the target set, below-deck ammunition handling, and the Mod 4 upgrade path for later destroyers and export fleets.

Target set

The U.S. Navy describes the mount as a fully automatic naval gun for surface, air, and land-attack or naval surface fire-support targets.

Source: MK 45 - 5-inch 54/62 Caliber Guns.

Ammunition depth

The Navy fact file lists 600 conventional rounds on destroyers and 1,200 conventional rounds on cruisers.

Source: MK 45 - 5-inch 54/62 Caliber Guns.

Mod 4 upgrade path

BAE Systems identifies DDG 81 and later ships as forward-fit applications and says existing Mod 0-2 mounts can be upgraded to Mod 4.

Source: Mk 45 Mod 4 Naval Gun System.

Timeline

Mark 45 5-inch naval gun Key Events

  1. Carney Mk 45 fire reported in Libya campaign

    USNI News reported that USS Carney fired illumination rounds from its MK 45 5-inch lightweight gun while supporting U.S. strikes against Islamic State targets in Sirte, Libya.

    Sources: USNI Carney Mk 45 Libya support

  2. Carney fires main 5-inch gun in Red Sea engagement

    The U.S. Navy account of USS Carney's Oct. 19, 2023 Red Sea battle describes the destroyer's main 5-inch gun firing during an engagement with Houthi missiles and UAVs.

    Sources: USS Carney Red Sea combat account

  3. Stockdale five-inch gun drone kill disclosed

    USNI News reported Vice Adm. Brad Cooper's account that USS Stockdale sailors used the destroyer's five-inch gun to shoot down a Houthi UAV during a November 2024 attack.

    Sources: USNI Stockdale five-inch gun drone engagement

  4. Spruance disables M/V Touska with Mk 45 fire

    CENTCOM said USS Spruance fired several rounds from the destroyer's 5-inch Mk 45 gun into M/V Touska's engine room after the Iranian-flagged vessel failed to comply with blockade warnings.

    Sources: CENTCOM Spruance disables M/V Touska

Media

Mark 45 5-inch naval gun Videos

Mark 45 5-inch naval gun Images

Mark 45 5-inch naval gun, Naval gun, Artillery - view 1
Source: USS Milius Mark 45 live-fire photo
Mark 45 5-inch naval gun, Naval gun, Artillery - view 2
Source: USS Milius Mark 45 live-fire photo
Related Weapon Systems
114 mm Vickers Mark 8, Single-barrel dual-purpose naval gun, Naval SystemsNaval Systems114 mm Vickers Mark 8Single-barrel dual-purpose naval gunThe 114 mm Vickers Mark 8 is the Royal Navy's post-1970s single-barrel 4.5-inch naval gun, replacing the heavier Mark 6 twin mounting with a 55-calibre automatic system for surface fire, naval gunfire support, and limited air or force-protection roles. It served on Type 21, Type 22, Type 23, Type 42, Type 45, and export warships, with Falklands War use followed by later Mod 1 low-observable gunhouse upgrades and 2011 Libya combat firings by Royal Navy ships.
114 mm Vickers Mark 6, Dual-purpose naval gun turret, Naval SystemsNaval Systems114 mm Vickers Mark 6Dual-purpose naval gun turretThe 114 mm Vickers Mark 6 was the postwar designation for the QF 4.5-inch Mark V gun carried in the Mark VI twin mounting, a British dual-purpose naval turret built around high-angle fire, remote power control, and rapid surface, air, and shore engagement. It entered service in 1947, equipped British and Commonwealth destroyers and frigates, and remained relevant in the 1982 Falklands War as Royal Navy escorts used 4.5-inch naval gunfire for shore support and surface engagements.
20mm Mk 15 Phalanx, Shipboard close-in weapon system, Naval SystemsNaval Systems20mm Mk 15 PhalanxShipboard close-in weapon systemThe 20mm Mk 15 Phalanx is a U.S.-origin shipboard close-in weapon system built around an M61A1 Gatling gun, self-contained search and track radar, and automated fire-control functions. Navy and manufacturer sources describe it as the U.S. Navy's inner-layer defense against anti-ship missiles, aircraft, unmanned aircraft, and small surface threats; direct combat-use evidence includes USS Jarrett's Gulf War Phalanx firing during the Iraqi Silkworm engagement near USS Missouri and USS Gravely's Red Sea interception of a Houthi anti-ship missile.

Sources

MK 45 - 5-inch 54/62 Caliber GunsPublisher: U.S. Navy | Note: Supports Mark 45 background, primary function, target set, Mod 0 deployment date, range, rate of fire, caliber, firing-control systems, ready-loader depth, and destroyer/cruiser magazine capacities. | Accessed: 2026-07-06Destroyers (DDG 51)Publisher: U.S. Navy | Note: Supports the Arleigh Burke-class guided-missile destroyer armament context used to link the Mark 45 to DDG 51-class ships. | Accessed: 2026-07-06Mk 45 Mod 4 Naval Gun SystemPublisher: BAE Systems | Note: Supports Mark 45 Mod 4 manufacturer context, 62-caliber upgrade features, DDG 81 onward forward-fit context, export fleet applications, Mod 0-2 upgrade path, and extended-range Mod 4 context. | Accessed: 2026-07-06Mk 45 Mod 4 datasheetPublisher: BAE Systems | Note: Supports Mark 45 Mod 4 weight and mount characteristics. | Accessed: 2026-07-06RAND Naval Surface Fire Support AssessmentPublisher: RAND Corporation | Note: Supports DDG 51-class Mk 45 mounting context and the distinction between Mod 2 and Mod 4 DDG 51 installations. | Accessed: 2026-07-06USNI Carney Mk 45 Libya supportPublisher: USNI News | Note: Used by USS Carney during the 2016 U.S. Campaign Against ISIS in Libya; USNI News reported that Carney supported Operation Odyssey Lightning near Sirte and fired illumination rounds from its MK 45 5-inch lightweight gun while supporting strikes against Islamic State targets. | Accessed: 2026-07-06USS Carney Red Sea combat accountPublisher: U.S. Navy | Note: Used by USS Carney during the 2023 Red Sea Crisis; the Navy account describes the destroyer's main 5-inch gun firing during an Oct. 19, 2023 engagement with Houthi missiles and UAVs and identifies a Mk. 45 gun technician assigned to Carney. | Accessed: 2026-07-06USNI Stockdale five-inch gun drone engagementPublisher: USNI News | Note: Used by USS Stockdale during the 2023 Red Sea Crisis; USNI News reported that sailors with USS Stockdale used the destroyer's five-inch gun to shoot down a Houthi uncrewed aerial vehicle. | Accessed: 2026-07-06Operation Epic Fury: USS Milius Mark 45 live-firePublisher: U.S. Central Command | Note: Fired by USS Milius during Operation Epic Fury in the 2020 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: 2026-07-06CENTCOM Spruance disables M/V TouskaPublisher: U.S. Central Command | Note: Used by USS Spruance during the 2020 United States-Iran Conflict; CENTCOM said Spruance fired several rounds from the destroyer's 5-inch Mk 45 gun into M/V Touska's engine room during blockade enforcement. | Accessed: 2026-07-06USS Milius Mark 45 live-fire photoPublisher: U.S. Navy | Note: Supports image provenance for the USS Milius Mark 45 live-fire photo. | Accessed: 2026-07-06USS Milius live-fire photoPublisher: U.S. Navy | Note: Supports image provenance for the later USS Milius live-fire photo. | Accessed: 2026-07-06USS Milius Philippine Sea live-fire photoPublisher: U.S. Navy | Note: Supports image provenance for the USS Milius Philippine Sea live-fire photo. | Accessed: 2026-07-06