Developed for the German Army in the 1960s and used on Marder Armored Personnel Carriers. Adapted for ship-board use in the 1970s. Gas-operated with a rigid bolt, this weapon is designed for minimal recoil forces and long barrel life. Available in either single or dual belt versions. Originally built by Rhinemetall. MK stands for "Maschinenkanone."

Gun Characteristics

Designation Gun: 20 mm/65 (0.8") MK 20 DM 5
Ship Class Used On Present-day German warships
Date Of Design 1962 (1973 Naval Version)
Date In Service 1974 (Naval Version)
Gun Weight 167.5 lbs. (76 kg)
Gun Length oa 102.8 in (2.612 m)
Bore Length N/A
Rifling Length 66.9 in (1.700 m)
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 1,000 rounds per minute cyclic


Type Fixed
Weight of Complete Round N/A
Projectile Types and Weights HE-T: 0.3 lbs. (0.134 kg)
AP-T: 0.3 lbs. (0.134 kg)
APDS-T: 0.3 lbs. (0.134 kg)
Bursting Charge N/A
Projectile Length N/A
Length of Complete Round: 8.4 in (21.3 cm)
Propellant Charge 0.092 lbs. (0.42 kg)
Cartridge 20 x 139 mm NATO
Muzzle Velocity HE-T: 3,440 fps (1,050 mps)
AP-T: 3,600 fps (1,100 mps)
APDS-T: 3,770 fps (1,150 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun Ammunition in 200 round belts


Range with 0.3 lbs. (0.134 kg) HE
Elevation Distance
Effective 2,200 yards (2,000 m)
Maximum 6,400 yards (7,000 m)

Mount / Turret Data

Designation Rheinmetall single pintle fork mounting: S 20 and SV 20
Norwegian Single Mounts: KV-Sk/20 1
Weight Rheinmetall S 20
   Without gun or ammunition: 617 lbs. (280 kg)
   With gun and 200 rounds ammunition: 948 lbs. (430 kg)

Rheinmetall SV 20: N/A

   KV-Sk/20: Without ammunition: 880 lbs. (400 kg)

Elevation Rheinmetall: -10 / +55 (or +60) degrees
Norwegian: -15 / +70 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil N/A
  • ^The Norwegian version is based upon the FK20-2 field-gun mounting. Norway also uses this gun in their coastal defense units to provide protection to larger guns from land and air attacks.

Additional Pictures


"The Naval Institute Guide to World Naval Weapon Systems 1991/92" by Norman Friedman
"Jane’s Armour and Artillery 1985–86" by C.F. Foss (editor)
Mauser Weapon Systems
Rheinmetall AG
Special help by Jakko Westerbeke

Page History

28 December 2008 - Benchmark
07 September 2019 - Converted to HTML 5 format, added gun details
03 May 2022 - Added photograph of twin mount