Not to be confused with the Oerlikon 20 mm gun used by the Allies, these German 2 cm weapons were manufactured by Rheinmetall. The Rheinmetall design was developed from an earlier Solothurn weapon, the ST-5. Both the C/30 and the C/38 guns were fully automatic.

The C/30 model was prone to jamming and used a small magazine (20 rounds) which meant frequent pauses for reloading. The later C/38 was a much improved weapon which used a 40 round magazine. A very successful variation of this weapon was the Flak 38, (Naval Flak 35), which combined four C/38 guns in a single quad mounting. A three-dimensional stabilized naval-mount designated as the Vierling C38/43 was introduced in 1944.

The C/38 was also produced in very sophisticated twin mount for U-boats. These were able to withstand a 550 foot (200 m) diving depth.

Gun Characteristics

Designation 2 cm/65 (0.79") C/30
2 cm/65 (0.79") C/38
Ship Class Used On Almost all
Date Of Design 1930 / 1938
Date In Service 1934 / 1940
Gun Weight C/30: 141 lbs. (64 kg)
C/38: 129 lbs. (57.5 kg)
Gun Length oa 88.7 in (2.2525 m)
Bore Length 51.2 in (1.300 m)
Rifling Length 46.7 in (1.159 m)
Number Of Grooves (8) 0.0128 in deep x 0.205 in (0.325 mm x 5.2 mm)
Lands 0.104 in (2.65 mm)
Twist Uniform RH 1 in 36
Chamber Volume 2.93 in3 (0.048 dm3)
Rate Of Fire C/30
   280 rounds per minute cyclic
   120 rounds per minute practical

   480 rounds per minute cyclic
   220 rounds per minute practical


Type Fixed
Weight of Complete Round 0.71 lbs. (0.320 kg)
Projectile Types and Weights HE-I: 0.265 lbs. (0.120 kg)
HE-T: 0.256 lbs. (0.116 kg) 1
AP-I: 0.326 lbs. (0.148 kg)
Bursting Charge HE-I: 0.013 lbs. (6.0 gm) PETN + 0.031 lbs. (14.0 gm) Incendiary
HE-T: 0.013 lbs (5.9 gm) PETN
Projectile Length 3.1 in (7.85 cm)
Complete Round: 8.99 in (22.8 cm)
Propellant Charge 0.265 lb. (0.120 kg) RPC/38
Cartridge Case Type, Size and Empty Weight Brass, 20 x 138B mm, 0.41 lbs. (0.186 kg)
Muzzle Velocity HE-I: 2,740 fps (835 mps)
AP-I: 2,625 fps (800 mps)
Working Pressure 17.8 tons/in2 (2,800 kg/cm2)
Approximate Barrel Life 20,000 - 22,000 rounds
Ammunition stowage per gun 2,000 rounds 2
  • ^Early tracer burned for 5.5 seconds for an altitude of about 6,550 feet (2,000 m). Later tracer burned for 6.0 seconds for an altitude of about 7,220 feet (2,200 m).
  • ^Outfits were about 75% HEI and 25% API.
  • The sources listed below differ as to the ammunition weights, muzzle velocities, propellants and ranges. I have chosen to use those given in "German Destroyers of World War Two" and in TM E 9-9228.


Range with 0.300 lbs. (0.134 kg) HE
Elevation Distance
45 degrees 5,360 yards (4,900 m)
AA Ceiling @ 85 degrees 12,140 feet (3,700 m)

Mount / Turret Data

Designation Single Mount for C/30 and C/38: Pedestal C/30
Twin Mount for C/38: Flakzwilling C/38
Quad Mount for Flak 35: Vierling C/38 1a
Quad 3-D stabilized Mount: Vierling C38/43 2a
U-boat twin mount: LM44U 3a
S-boat single mount: L41
Weight L/30 with C/30 gun: 926 lbs. (420 kg)
L/30 with C/38 gun: 917 lbs. (416 kg)
Twin Mount Flakzwilling: N/A
Quad Mount Flak 35: 4,740 lbs. (2,150 kg)
LM44U: 7,937 lbs. (3,600 kg)
L41: 1,100 lbs. (500 kg)
Elevation 4a Single Mount: -11 / +85 degrees
Twin Mount Flakzwilling: N/A
Quad Mount Flak 35: -10 / +90 degrees
LM44U: -10 / +78 degrees
L41: -10 / +85 degrees
Elevation Rate All except LM44U: Manually operated, only
LM44U: 30 or 60 degrees per second
Train 360 degrees
Train Rate All except LM44U: Manually operated, only
LM44U: 30 degrees per second
Gun recoil N/A
  • ^In the quadruple Flak 35 mounting, distance between gun axes was 67.4 cm (26.5 inches) horizontally and 28 cm (11.0 inches) vertically.
  • ^The Naval quad mount Vierling C38/43 was tri-axial stabilized and differed from the Army version by having both an azimuth and an elevation setter, with both crewmen located in front of the mount. There was also an angle setter, who manned a large handwheel on the left side of the mounting which was used to compensate for the rolling and pitching of the ship.
  • ^The LM44U had hydraulic training and elevation controlled by a joy-stick. Foot pedals operated the triggers. The mounting was bi-axial, somewhat surprising given the sophistication of the design.
  • ^The Army Flakvierling 38 carriage had an elevation range of -10 / +110 degrees.

Additional Pictures


"Naval Weapons of World War Two" by John Campbell
"German Warships 1815-1945" by Erich Gröner
"German 20mm FLAK in World War II" by Werner Müller
"German Destroyers of World War Two (2nd Edition)" and "German Coastal Forces of World War Two" both by M.J. Whitley
"2 cm Flakvierling 38 (German 20-MM Antiaircraft Gun, Four-Barreled Mount)" by US War Department, Publication TM E 9-9228, 1 April 1943
Special help from Peter Lienau and Robert Hurst

Page History

05 May 2007 - Benchmark
20 May 2012 - Updated to latest template
12 February 2015 - Added note regarding elevation range of Army quad mounting
13 March 2015 - Added Flakvierling sketch
23 February 2018 - Converted to HTML 5 format and reorganized notes
13 April 2020 - Added photograph of Naval Quad mount
13 November 2021 - Added burster weights