45 mm anti-aircraft gun (21-K)
A 21-K on board the Krasny Kavkaz
TypeAnti-aircraft cannon
Place of originSoviet Union
Service history
In service1934—?
Used bySoviet Union
WarsSecond World War, Cold War
Production history
Designed1932—34
Produced1934—1947
No. built2799
Variants40-K, 41-K
Specifications
Mass107–115 kilograms (236–254 lb)
Length2.3975 metres (7.866 ft)
Barrel length2.0725 metres (6.800 ft)
Shell45×386 mm. SR
Shell weight1.065–2.14 kg (2.35–4.72 lb)
Caliber45 millimetres (1.8 in)
Actionsingle-shot
Breechsemi-automatic, vertical sliding-block
Elevationdepends on the mount
Traverse360°
Rate of fire25-30 rpm (practical)
Muzzle velocity880 metres per second (2,900 ft/s)
Effective firing range6,000 m (20,000 ft) (maximum ceiling)
Maximum firing range9,200 metres (10,100 yd) at 45°

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 (1.5 in) 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 (1.8 in) 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-caliber21-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.[1] 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.[2]

Description

The 21-K, complete with its pedestal, weighed 507 kg (1,118 lb). 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 2,000 kg (4,400 lb) and the 41-K was a twin-gun turret that weighed 2,600 kg (5,700 lb). 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.[2]

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.[2]

Shell name Type Weight Filling Weight Muzzle velocity
BR-240 armor-piercing 1.42 kg (3.1 lb) 18 g (0.63 oz) 760 m/s (2,500 ft/s)
OT-033 Fragmentation-tracer 1.065 kg (2.35 lb) 52 g (1.8 oz) 880 m/s (2,900 ft/s)
OR-73A Fragmentation-tracer 1.41 kg (3.1 lb) 37 g (1.3 oz) 760 m/s (2,500 ft/s)
F-73 High-explosive 1.41 kg (3.1 lb) 74 g (2.6 oz) 760 m/s (2,500 ft/s)
O-240 High-explosive 2.14 kg (4.7 lb) 118 g (4.2 oz) 335 m/s (1,100 ft/s)

See also

Notes

  1. ↑ Breyer, p. 275
  2. 1 2 3 "Russian 45 mm/46 (1.77") 21-K". 13 May 2006. Retrieved 21 July 2009.

References

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