Planned for the "13" class battleships of the 8-8-8 plan, none of these ships or guns were ever built. Guns were of wire-wound construction. These guns are sometimes confused with the prototype 48 cm (18.9") 5th Year Type gun built in the early 1920s.

All work on guns of these sizes was halted by the Washington Naval Limitation Treaty and the ships were cancelled in the Spring of 1922.

Some sources quote a caliber length of 45 or 47.9 calibers, but the barrel sketch below shows that the gun had a length of 50 calibers.

Gun Characteristics

Designation 46 cm/50 5th Year Type (Model 1916)
Official Designation: 50 caliber 5th Year Type 46 cm Gun
Ship Class Used On "13" Class Battleships (Battleships 39-42, also known as Battlecruisers 13-16)
Date Of Design about 1918
Date In Service N/A (planned for completion in 1927)
Gun Weight N/A
Gun Length oa 931.1 in (23.650 m)
Bore Length 905.5 in (23.000 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire about 1.5 rounds per minute


Type Bag
Projectile Types and Weights APC - about 3,000 lbs. (1,360 kg)
Bursting Charge N/A
Projectile Length APC - 63 in (160 cm)
Propellant Charge N/A
Muzzle Velocity N/A
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun About 60 rounds


Range of APC projectiles
Elevation Range
Elevation about 3,000 lbs. (1,360 kg) AP Shell
30 degrees about 36,000 yards (32,920 m)

Mount/Turret Data

Designation Two-gun Turrets
  "13" (4)
Weight about 1,181 tons (1,200 mt)
Elevation about -3 / +35 degrees
Elevation Rate N/A
Train About +150 / -150 degrees
Train Rate N/A
Gun recoil N/A
  1. Gun axes were 114 in (290 cm) apart.
  2. Turret Armor as shown below in the turret sketch:
      Front: 14 in (35.6 cm)
      Fore Sides: 7.5 in (19.0 cm)
      Rear Sides: 7.5 in (19.0 cm)
      Rear: 7.5 in (19.0 cm)
      Roof: 6.0 in (15.2 cm)
      Base: 4.0 in (10.2 cm)
    The front of the turret had a semi-circular armor "lip" to protect the top of the barbette.

Additional Pictures


"Naval Weapons of World War Two" by John Campbell
"Japanese Warships of World War II" by A.J. Watts
Tony DiGiulian's personal data files
Yuzuru Hiraga Digital Archive
Special help from TZoli

Page History

23 December 2006 - Benchmark
23 June 2012 - Updated to latest template
03 November 2016 - Converted to HTML 5 format, added a few details and sketches from the Yuzuru Hiraga Digital Archive