The 7.7 mm "RU" Type was the famous Lewis machine gun imported from Britain starting in 1921. The design was modified to suit local Japanese manufacturing techniques and then produced as the 7.7 mm Type 92. These guns replaced the 6.5 mm 3rd Year Type MG on most ships.

Actual bore diameter was 0.303" (7.69 mm).

Gun Characteristics

Designation 7.7 mm/87 (0.303") "RU" Type
7.7 mm/80 (0.303") Type 92 (Model 1932)
Ship Class Used On Many ships of the 1920s and 1930s
Date Of Design N/A
Date In Service 1921
Gun Weight "RU" Type: 26.0 lbs. (11.79 kg)
Type 92: 28.7 lbs. (13.00 kg)
Gun Length oa "RU" Type: 50.5 in (1.283 m)
Type 92: 39.4 in (1.000 m)
Bore Length "RU" Type: 26.3 in (0.667 m)
Type 92: 24.4 in (0.620 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire "RU" Type: 550 rounds per minute
Type 92: 600 rounds per minute


Type Fixed
Weight of Complete Round N/A
Projectile Types and Weights Solid bullet: 0.025 lbs. (11.35 gms)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity "RU" Type: 2,444 fps (745 mps)
Type 92: 2,493 fps (760 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A


Range with 0.025 lbs. (11.35 gms) Bullet
Elevation Distance
Maximum Range "RU" Type: 1,000 yards (910 m)
Type 92: 1,090 yards (1,000 m)
Effective Range "RU" Type: 540 yards (490 m)
Type 92: 328 yards (300 m)

Mount/Turret Data

Designation Single Mounts
Weight N/A
Elevation About -25 / +85 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil N/A


Data from:

  • "World War II Fact Files: Machine-Guns" by Peter Chamberlain and Terry Gander
  • "Japanese Cruisers of the Pacific War" by Eric Lacroix and Linton Wells II

Special help from Paul Roome

Page History

10 May 2006
27 May 2012
Updated to latest template