Germany
2 cm/65 (0.79") C/30
2 cm/65 (0.79") C/38 AA MG
Updated 20 May 2012
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 35, which combined four C/38 guns in a single quad mounting.  A three-dimensional stabilized naval-mount 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.
WNGER_20mm-65_c30_bag_pic.jpg

2 cm/65 C30 showing 20-round magazine
The sailor at the lower left is holding a rangefinder.  The bag is to catch expended shell casings.
Photograph courtesy of Peter Lienau
.
Click here for additional pictures
.
.
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
Rate Of Fire - C/38 480 rounds per minute cyclic 
220 rounds per minute practical
.
Ammunition
.
Type Fixed
Weight of Complete Round 0.71 lbs. (0.320 kg)
Projectile Types and Weights HEI - 0.300 lbs. (0.134 kg)
API - 0.326 lbs. (0.148 kg)
Bursting Charge N/A
Projectile Length 3.1 in (7.85 cm)
Propellant Charge 0.265 lb. (0.120 kg) RPC/38
Cartridge - 0.41 lbs. (0.186 kg)
Muzzle Velocity HEI:  2,740 fps (835 mps)
API:  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
Notes:

1) Outfits were about 75% HEI and 25% API.

2) 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."
.
Range
.
Elevation With 0.300 lbs. (0.134 kg) HE Shell
Range @ 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 L/30 
Quad Mount for Flak 35: Vierling L/38
Quad 3-D stabilized Mount:  Vierling C 38/43
U-boat twin mount:  LM44U
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) 
Quad Mount Flak 35:  4,740 lbs. (2,150 kg)
LM44U:  7,937 lbs. (3,600 kg)
L41:  1,100 lbs. (500 kg)
Elevation Single Mount:  -11 / +85 degrees
Vierling:  -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
Notes:

1) 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.

2) In the quadruple Flak 35 mounting, distance between gun axes was 67.4 cm (26.5 inches) horizontally, 28 cm (11.0 inches) vertically.
.
Data from
"Naval Weapons of World War Two" by John Campbell
"German Warships 1815-1945" by Erich Gröner
"German Destroyers of World War Two (2nd Edition)" and "German Coastal Forces of World War Two" both by M.J. Whitley
---
Special help from Peter Lienau and Robert Hurst
Page History

05 May 2007 - Benchmark
20 May 2012 - Updated to latest template