3.7 cm Flak 43
A Flak 43 Zwilling in Northern France, mid-1944
Type	Anti-aircraft gun
Place of origin	Nazi Germany
Service history
In service	1944-1945
Used by	Germany
Wars	World War II
Production history
Designer	Rheinmetal-Borsig
Designed	1939–1943
Produced	1944–1945
Specifications
Mass	355 kg (783 lb)
Barrel length	2.106 m (82.9 in) (57 calibers)
Crew	3–4
Shell	37 × 263B
Shell weight	635–700 g (1.4–1.5 lb)
Caliber	37 mm (1.5 in)
Breech	Gas-operated
Elevation	-10° to +90°
Traverse	360°
Rate of fire	250 rounds per minute (cyclic) 180 rounds per minute (practical)
Muzzle velocity	790–820 m/s (2,600–2,700 ft/s)
Effective firing range	6,585 m (7,201 yd) (ground targets) 4,800 m (15,700 ft) (ceiling)
Feed system	8-round clips

The 3.7 cm Flak 43 was a light anti-aircraft (AA) gun used by Nazi Germany during World War II. It was derived from the 3.7-centimeter (1.5 in) Flak 18/36/37 series of AA guns. It was provided with single- and twin-gun mounts, the latter being designated as the 3.7 cm Flak 43 Zwilling and was in service from 1944 to 1945. In addition to versions used by the Kriegsmarine (German Navy), it served as the main armament of the Ostwind and Möbelwagen and was proposed for use in the Flakpanzer Coelian self-propelled AA guns.

Background and description

Rheinmetall-Borsig redesigned the Flak 36/37 to incorporate the gas-operated breech mechanism of the 3-centimeter (1.18 in) MK 103^[1] and to reduce the number of man-hours required to manufacture it from 4320 to 1000.^[2] The most obvious change was the adoption of a horizontal feed system from the vertical system of the earlier guns. The feed tray was positioned inside the oversized trunnions at the gun's center of gravity so it could be reloaded without disturbing the gun's aim. These changes significantly lightened the gun and made it faster to traverse and elevate.^[2]

Naval use

The Kriegsmarine used a version of it on surface ships as the 3.7 cm Flak M43 in its own single- and twin-gun mounts; its Flak LM 44 mount had the guns side-by-side, unlike the Zwilling.^[3]

Service

The first Flak 43s were reported in Luftwaffe service in August 1944, 431 single guns and 41 Zwilling mounts. By February 1945, these increased to 1032 single guns and 380 Zwillings.^[4]