180mm Pattern 1931-1933

180mm Pattern 1931-1933
MK-1-180 single turrets aboard the Soviet light cruiser Krasnyi Kavkaz
Type	Naval gun Coastal artillery Railway gun
Place of origin	Soviet Union
Service history
In service	Soviet Union
Used by	Soviet Union
Wars	World War II
Production history
Designed	1929
Produced	1931-1933
Variants	180mm/60 Pattern 1931 180mm/57 Pattern 1932 180mm/56 Pattern 1933
Specifications
Weight	17–18.5 t (18.7–20.4 short tons)
Length	10.2–10.6 m (33–35 ft)
Barrel length	8–8.2 m (26–27 ft)
Shell	Separate loading bagged charge and projectile
Shell weight	97.5 kg (215 lb)
Caliber	180 mm (7.1 in) 56-60 Caliber
Elevation	Single naval mounts: -5°to +60° Triple naval mounts: -5° to +50° Coastal & Rail mounts: -0° to +50°
Rate of fire	4-5 rpm
Muzzle velocity	900 m/s (3,000 ft/s)
Maximum firing range	37.1–38.5 km (23.1–23.9 mi) at +50°

The 180mm Pattern 1931-1933 were a family of related naval guns of the Soviet Navy in World War II, which were later modified for coastal artillery and railway artillery roles. They were the primary armament of the Soviet Union's first cruisers built after the Russian Civil War.

The 180mm Pattern 1931-1933 weren't a single model of gun, but instead were a family of related guns, either built from converted 203 mm (8.0 in)/50 Pattern 1905 guns which were relined down to 180 mm (7.1 in) or they were newly built guns. The original guns were constructed of a three piece A tube, reinforced by two layers of outer tubes and a jacket. The lengths of these guns varied between 56-60 calibers and their weights varied, but their performance was similar.

180mm/60 B-1-K Pattern 1931 - In 1927 work on the former Imperial Russian Navy Admiral Nakhimov-class cruiser Krasnyi Kavkaz was restarted after being halted in 1917 following the October Revolution. It had been planned to arm the Krasnyi Kavkaz with eight 203mm guns in double turrets, but it was found impossible to mount this much armament on such a small and lightly constructed hull. Instead four smaller caliber 180mm/60 B-1-K Pattern 1931 guns were mounted in single turrets. Early testing found that the muzzle velocity for these guns was abnormally high which reduced barrel life to only 55-70 rounds, so the guns were derated and smaller propellant charges were used.

180mm/57 B-1-P Pattern 1932 - Since the pattern 1931 wasn't satisfactory a new gun design with a lower muzzle velocity and shorter barrel length designated the 180 mm/57 B-1-P Pattern 1932 was produced. Early prototypes were of built-up construction, but in 1932 the technology for producing loose liners was purchased from the Italian firm of Ansaldo. Later 180 mm/57 B-1-P Pattern 1932 guns were constructed of a loose liner, A tube, jacket and breech ring. The 180 mm/57 B-1-P Pattern 1932 were manufactured with two different styles of liners, one had shallow rifling and the other had deep rifling, the two liners were not interchangeable and required different ammunition. The shallow rifled liners still only had a life of 55-70 rounds, but the deeply rifled liners had a life of 320 rounds.