German
3.7 cm/69 (1.5") M42
Updated 15 May 2006
This weapon was manufactured by Rheinmetal-Borsig and was essentially a longer barrel version of the Army 3.7 cm Flak 36.  This new gun was a great improvement over the older 3.7 cm/83 SK C/30 and had a much higher rate of fire.  Recoil operated, air cooled and used five-round ammunition strips.

These were the first German light anti-aircraft guns to have shields, a surprising shortcoming of earlier weapons.

The design of this gun emphasized ease of manufacturing.  Constructed of a monobloc barrel connected to the breech ring by a bayonet joint to allow easy replacement.  Used a vertical sliding breech block, hydraulic brake and spring recuperator.
WNGER_37mm-69_mk42_pic.jpg

Postwar photograph of Z39 showing two twin 3.7 cm Mark 42 guns
Note the USA Baltimore-class 8" (20.3 cm) turret in the background
WNGER_37mm-69_mk42_U-995_pic.jpg

3.7 cm/69 M42 on U-995
Note the feed guides, which were similar to those used for the 4 cm Bofors
Photograph courtesy of Dave Krakow
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Gun Characteristics
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Designation 3.7 cm/69 (1.5") M42
Ship Class Used On U-boats, Emden, destroyers and minesweepers
Date Of Design 1942
Date In Service 1944
Gun Weight 240 lbs. (109 kg)
Gun Length oa N/A
Barrel Length 100.79 in (2.560 m)
Rifling Length 90.1 in (2.289 m)
Grooves (20) 0.0217 in deep x 0.150 in (0.55 mm x 3.81 mm)
Lands 0.087 in (2.2 mm)
Twist Uniform RH 1 in 25.6
Chamber Volume 16.5 in3 (0.270 dm3)
Rate Of Fire 250 rounds per minute cyclic
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Ammunition
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Type Fixed
Weight of Complete Round HE tracer -  3.0 lbs. (1.36 kg)
HE incendiary - 3.02 lbs. (1.37 kg)
AP tracer - 3.31 lbs. (1.50 kg)
Projectile Types and Weights HE tracer - 1.40 lbs. (0.635 kg)
HE incendiary - 1.42 lbs. (0.640 kg)
AP tracer - 1.54 lbs. (0.700 kg)
Bursting Charge HE tracer - N/A
HE incendiary - N/A
AP tracer - N/A (probably solid bullet)
Projectile Length N/A
HE incendiary, complete round - 14 in (355 mm)
Propellant Charge 0.386 lbs. (0.175 kg) RPC/38N
Cartridge - 1.0 lbs. (0.51 kg)
Muzzle Velocity HE tracer - 2,838 fps (865 mps)
HE incendiary - 2,772 fps (845 mps)
AP tracer - 2,674 fps (815 mps)
Working Pressure 18.7 tons/in2 (2,950 kg/cm2)
Approximate Barrel Life 7,000 rounds
Ammunition stowage per gun 2,000 rounds
Notes:

1) The sources below differ in many areas for this weapon.  The figures given in this table come mainly from "Naval Weapons of Word War Two."
2) Minesweeper outfits were half AP tracer and half HE tracer.  Outfits on other ships was intended to be two-thirds HE incendiary and one-third AP tracer.
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Range
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Elevation With 1.34 lbs. (0.61 kg) HE Incendiary Shell
Range @ 45 degrees 7,000 yards (6,400 m)
AA Ceiling @ 85 degrees 17,750 feet (4,800 m)
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Mount / Turret Data
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Designation Single Mount:  N/A
Twin Mount:  3.7 cm Flak LM/42
Weight  Single:  N/A
Twin:  1.33 tons (1.35 mt)
Elevation -10 / +90 degrees
Elevation Rate Manual operation, only
Train 360 degrees
Train Rate Manual operation, only
Gun recoil N/A
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Data from
"Naval Weapons of World War Two" by John Campbell
"German Warships 1815-1945" by Erich Gröner
"Das Buch der Deutschen Kriegsmarine" by Jak P. Mallmann Showell
"German Destroyers of World War Two (2nd Edition)" and "German Cruisers of World War Two" both by M.J. Whitley
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Special help by Dave Krakow