Bag gun later modified to use semi-fixed ammunition. Used as secondaries on Chicago, one of the "New Navy" cruisers built in the 1880s. This was one of the first steel-tube naval guns built entirely in the USA. Two guns were built.

The original Mark I guns had trunnions and no liner. The trunnions were later cut off and a liner inserted, converting the weapon to fixed ammunition. At that time, the guns consisted of liner, tube, jacket and nine hoops. The hooping began 3.5 inches (9 cm) from the breech and stopped 59.5 inches (151 cm) from the muzzle. There was no muzzle bell. Used a Dashiell Mark II Mod 2 breech mechanism.

Gun Characteristics

Designation 5"/31 (12.7 cm) Mark 1
Ship Class Used On Chicago
Date Of Design about 1885
Date In Service 1886
Gun Weight 6,190 lbs. (2,808 kg) without breech
Gun Length oa N/A
Bore Length about 155 in (3.937 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire about 6 rounds per minute


Type Bag (later semi-fixed)
Projectile Types and Weights AP: 50 lbs. (22.7 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 10 lbs (4.5 kg)
Muzzle Velocity 2,300 fps (701 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A


Range with 50 lbs. (22.7 kg) Shell
Elevation Range
30 degrees 16,000 yards (14,630 m)

Mount/Turret Data

  • Single Mounting with Gravity Return
    • Chicago (2): Mark 1
Weight N/A
Elevation N/A
Elevation Rate Manual operation, only
Train about +150 / -150 degrees
Train Rate Manual operation, only
Gun recoil N/A


Data from:

  • "U.S. Cruisers: An Illustrated Design History" and "US Naval Weapons" both by Norman Friedman
  • "United States Naval Guns: Their Marks and Modifications" Ordnance Pamphlet No. 127, December 1916, Second Revision June 1924
  • Gene Slover's Navy Pages