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45 mm anti-aircraft gun (21-K)

Field	Value
name	45 mm anti-aircraft gun (21-K)
image	21-K-KrasnyyKavkaz1.jpg
image_size	300
caption	A 21-K on board the Krasny Kavkaz
origin	Soviet Union
type	Anti-aircraft cannon
is_ranged	yes
is_artillery	yes
service	1934—?
used_by	Soviet Union
wars	Second World War, Cold War
design_date	1932—34
production_date	1934—1947
number	2799
variants	40-K, 41-K
weight	107 -
length	2.3975 m
part_length	2.0725 m
cartridge	45×386 mm. SR
cartridge_weight	1.065 -
caliber	45 mm
action	single-shot
rate	25-30 rpm (practical)
velocity	880 m/s
range	6000 m (maximum ceiling)
max_range	9200 m at 45°
breech	semi-automatic, vertical sliding-block
elevation	depends on the mount
traverse	360°

The 45 mm anti-aircraft gun (21-K) was a Soviet design adapted from the 45 mm anti-tank gun M1932 (19-K). This was a copy of a 3.7 cm German weapon designed by Rheinmetall that was sold to the Soviets before Hitler came to power in 1933 that had been enlarged to 45 mm to reuse a large stock of old 47mm ammunition. It was used by the Soviet Navy to equip almost all of their ships from 1934 as its primary light anti-aircraft gun until replaced by the fully automatic 37 mm 70-K gun from 1942 to 1943. It was used in World War II and during the Cold War as the Soviets exported their World War II-era ships to their friends and allies. However it was not very effective as its slow rate of fire and lack of a time fuze required a direct hit to damage targets.

Design

The 46-caliber 21-K was a minimal adaptation of the 53-K anti-tank gun that was created by taking the latter's barrel and mounting it on a simple pedestal mount. Its semi-automatic breech automatically ejected the cartridge case and locked open, ready for the next round. This was less than ideal for an anti-aircraft weapon that relied on its rate of fire to inflict damage on aircraft because every round had to be hand-loaded. Fully automatic weapons of roughly this caliber like the 40 mm Bofors typically used 4-5 round clips of ammunition to produce rates of fire four times as high.

Early production guns had a built-up barrel, but later ones used a monobloc. There were problems with the breech mechanism early in the production run and a number of the first year's production run lacked the semi-automatic breech entirely.

Description

The 21-K, complete with its pedestal, weighed 507 kg. It was manually operated and could elevate between -10° and +85° at a rate between 10 and 20 degrees per second. It could traverse a full 360° at a rate between 10 and 18 degrees per second, although this was practically limited by its actual location on ship. In the mid-1930s special powered turrets were developed for use on river monitors. The 40-K was a single gun turret that weighed 2000 kg and the 41-K was a twin-gun turret that weighed 2600 kg. Both turrets could elevate between -5° and +85° at a rate of 8 degrees per second and could traverse a full 360° at a rate between 4.8 and 9.8 degrees per second.

Ammunition

The 21-K used the same ammunition as the 45 mm anti-tank gun M1937 (53-K). The biggest problem in its role as an anti-aircraft gun was that it wasn't provided with a time fuze that would detonate the shell at a specified distance from the gun. This meant that only a direct hit would damage its target.

Shell name	Type	Weight	Filling Weight	Muzzle velocity
BR-240	armor-piercing	1.42 kg	18 g	760 m/s
OT-033	Fragmentation-tracer	1.065 kg	52 g	880 m/s
OR-73A	Fragmentation-tracer	1.41 kg	37 g	760 m/s
F-73	High-explosive	1.41 kg	74 g	760 m/s
O-240	High-explosive	2.14 kg	118 g	335 m/s

Notes

References

{{cite book

References

Breyer, p. 275
(13 May 2006). "Russian 45 mm/46 (1.77") 21-K".

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

45-mm-artillery naval-anti-aircraft-guns world-war-ii-anti-aircraft-guns world-war-ii-artillery-of-the-soviet-union anti-aircraft-guns-of-the-soviet-union military-equipment-introduced-in-the-1930s

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