Russia / USSR
305 mm/55 (12") B-36 Pattern 1937
305 mm/55 (12") B-50 Pattern 1940
Updated 16 April 2012

The B-36 was designed for use on the 1937 light battleship Project 25 in three MK-2 triple turrets, but the design was cancelled before the work on the gun and mounts had progressed very far.

The B-50 gun was based upon the B-36 gun and was intended to have been used by the never-built Kronshtadt (Pr. 69) class battlecruisers.  Very high muzzle velocity was to have given this gun an exceptionally long range, but probably at the cost of a very short liner life.

Design of this weapon started in 1938 at the Metal Factory, but was not finished before the start of World War II and no guns are known to have been started.  This was mainly as a result of the Molotov-Ribbentrop pact which changed the planned Kronshtadt armament to German 38 cm (14.96") guns.

Proposed construction consisted of tube, liner, breech casing and breech ring.  The breech was to have been a two stage, piston type.  Actual bore diameter was 304.8 mm (12.0").


Artist's conception of Kronshtadt

Gun Characteristics
Designation 305 mm/55 (12") B-36 Pattern 1937
305 mm/55 (12") B-50 Pattern 1940
Ship Class Used On B-36
   Project 25 Light BB

   Kronshtadt (Pr. 69) class

Date Of Design B-36: 1936-37
B-50: 1938
Date In Service Never entered service
Gun Weight 71.66 tons (72.8 mt)
[Some sources say 73.6 tons (74.8 mt)]
Gun Length oa 661.8 in (16.810 m)
Bore Length 655.2 in (16.640 m)
Rifling Length 514.8 in (13.077 m)
Grooves 40
Lands N/A
Twist N/A
Chamber Volume 15,870 in3 (260 dm3)
Rate Of Fire MK-2:  3 rounds per minute
MK-15:  3.24 rounds per minute
Note:  I consider the above ROF figures to have been design goals and not necessarily the firing rates that would have been achieved in service.
Type Bag
Projectile Types and Weights AP - 1,039 lbs. (471 kg)
HE - 838 lbs. (380 kg)
Light HE Round - N/A
Concrete Piercing - N/A
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 401 lbs. (182 kg)
Muzzle Velocity B-36
   Armor Piercing:  2,820 fps (860 mps)

   Light HE:  3,346 fps (1,020 mps)
   Concrete piercing:   2,953 fps (900 mps)
   Armor Piercing:  2,953 fps (900 mps)

Working Pressure 20 tons/in2 (3200 kg/cm2)
Approximate Barrel Life
(see Note 3)
300 (estimated)
Ammunition stowage per gun 100 rounds

1) The Light HE round was intended for coastal bombardment missions.

2) "Battleships"  Allied Battleships in World War II" lists a muzzle velocity of "2,900 fps (915 mps)," which is a bad Metric/English measurement conversion.  The figures used above are from "Encyclopedia of Russian Artillery."

3) Given the extremely high muzzle velocity and the lack of life extending enhancements like chromium plating, I cannot help but think that the actual barrel life of this gun would not have exceeded double digits.

Estimated Armor Penetration With 1,039 lbs. (471 kg) AP Shell
Side Armor
Deck Armor
10,000 yards (9,140 m)
21.00 in (533 mm)
0.55 in (14 mm)
20,000 yards (18,290 m)
14.76 in (375 mm)
1.73 in (44 mm)
30,000 yards (27,430 m)
11.00 in (280 mm)
3.46 in (88 mm)
Data from "Main Caliber of the Battleships."
Elevation With 838 lbs. (380 kg) HE Shell
Range @ 45  degrees 50,634 yards (46,300 m)
Elevation With 1,039 lbs. (470 kg) AP Shell
Range @ 45  degrees 52,030 yards (47,580 m)
Elevation With Light HE Shell
Range @ 45 degrees 60,040 yards (54,900 m)
Mount / Turret Data
Designation Three-gun mounts
   Project 25 (3):  MK-2
   Kronshtadt (3):  MK-15
Weight MK-2: 1,110 tons (1127.6 tons)
MK-15: 1,180 tons (1200 mt)
Elevation MK-2:  -2 / +45 degrees
MK-15:  -3 / +45 degrees
Rate of Elevation MK-2:  8 degrees per second
MK-15:  10 degrees per second
Train Turrets 1 and 2:  298-149 degrees
Turret 3 300-150 degrees.
Rate of Train MK-2: 5 degrees per second
MK-15: 5.1 degrees per second
Gun Recoil 47.2 in (120 cm)
Loading Angle +6 degrees
Data from
"Naval Weapons of World War Two" by John Campbell
"Battleships:  Allied Battleships in World War II" by W.H. Garzke, Jr. and R.O. Dulin, Jr.
"Sovetskie Boevye Korabli 1941-45:  IV Vooruzhnie" (Soviet Warships 1941-45:  Volume IV Armament) by A.V. Platonov
"Glavnyi Calibr Linkorov" (Main Caliber of the Battleships) by L.I. Amirkhanov and S.I. Titushkin
"Entsiklopedia Otechestvennoi Artillerii" (Encyclopedia of Fatherland (Russian) Artillery) by A.V. Shirokorad
Special help from Vladimir Yakubov
Page History

21 May 2006 - Benchmark
16 April 2012 - Updated to latest template