The 20F2 is the navalized version of the GIAT CN-MIT 20 M693 (Canon Mitrailleur 20 mm Modèle 693), formerly the Hispano-Suiza 820. This weapon is also used by the French Army.

The M621 is a low-recoil gun which has been mainly used on helicopters and small aircraft, but a navalized version was developed in the late 1980s. Recoil is minimized by the use of a muzzle brake and a shock-absorbing mount.

Gun Characteristics

Designation 20 mm/90 GIAT M693 CN-MIT-20F2
20 mm/73 GIAT M621
Ship Class Used On France: Florèal, Tripartite minelayers, P400, CDIC and EDIC classes
Belgium: Tripartite minelayers
Indonesia: Tripartite minelayers
Malawi: Kasunga
Netherlands: Tripartite minelayers
Pakistan: Tripartite minelayers
Saudi Arabia: NAJA 12 class
Date Of Design Late 1970s
Date In Service 20F2: 1983 (Naval Version)
M621: 1988 (Naval Version)
Gun Weight 20F2: N/A
M621: 104 lbs. (47 kg)
Gun Length oa 20F2: N/A
M621: 87 in (2.207 m)
Bore Length 20F2: about 71 in (1.800 m)
M621: about 57 in (1.460 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 20F2: 800 rounds per minute cyclic
M621: 740 rounds per minute cyclic


Type Fixed
Weight of Complete Round
  • 20F2:
    • HE: 0.562 lbs. (0.255 kg)
  • M621: N/A
Projectile Types and Weights
  • 20F2:
    • HE: 0.265 lbs. (0.120 kg)
    • APDS: 0.238 lbs. (0.108 kg)
  • M621: 0.223 lbs. (0.101 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity
  • 20F2:
    • HE: 3,440 fps (1,050 mps)
    • APDS: 4,100 fps (1,250 mps)
  • M621:
    • HE: 3,215 fps (980 mps)
    • AP: 3,380 fps (1,030 mps)
Working Pressure N/A
Approximate Barrel Life 16,000 rounds
Ammunition stowage per gun
(on mount)
20F2: 320 rounds in two 160-round magazines
M621: 160 rounds in single magazine


Range of 20F2
Elevation HE AP
Effective 2,200 yards (2,000 m) 1,300 yards (1,200 m)
Maximum 10,960 yards (10,020 m) 7,400 yards (6,770 m)

Mount/Turret Data

Designation 20F2: Affût 15B
M621: Affût 15A
Weight 15B: 688 lbs. (312 kg) without ammunition
15A: 417 lbs. (189 kg) without ammunition
Elevation 15B: -10 / +40 degrees
15A: -10 / +40 degrees
Elevation Rate Manual Elevation, only
Train -170 / +170 degrees
Train Rate Manual Training, only
Gun recoil N/A

These mountings use a collimator gunsight.

Additional Pictures


Data from:

  • "The Naval Institute Guide to World Naval Weapon Systems 1991/92" and "1994 Update" both by Norman Friedman
  • "Rapid Fire" by Anthony G. Williams


Page History

21 May 2006
03 March 2012
Updated to latest template