One of the first heavy guns of the "New Navy" of the late 1800s.

Mark 1 consisted of A tube, jacket, 19 hoops and an elevating band with integral trunnions. Mark 1 Mod 1 had no trunnions. The Mark 2 was similar, but had the hoops differently arranged, did not have integral trunnions and had its rear sights controlled by worm and miter gears.

Two guns from the cruiser Boston are currently (2019) on display at Hamlin Park in Shoreline, Washington. A plaque at the site states that one of these guns fired the first shot at the Battle of Manila Bay on 1 May 1898. See photograph below.

Gun Characteristics

Designation 8"/30 (20.3 cm) Marks 1 and 2
Ship Class Used On Atlanta and Chicago Classes
Date Of Design about 1883
Date In Service 1886
Gun Weight 29,100 lbs. (13,200 kg) not including breech
Gun Length N/A
Bore Length 240 in (6.096m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist Increasing RH 1 in 180 to 1 in 30 at the muzzle
Chamber Volume N/A
Rate Of Fire about 0.5 - 1 round per minute


Type Bag
Projectile Types and Weights AP - 260 lbs. (118 kg)
Common - 260 lbs. (118 kg)
Bursting Charge AP - 5.0 lbs. (2.3 kg) Black Powder
Common - 8.0 lbs. (3.6 kg) Black Powder
Projectile Length N/A
Propellant Charge 49.6 lbs. (22.5 kg)
Muzzle Velocity 2,000 fps (610 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun N/A


Ranges of Common projectiles
Elevation Range
20 degrees about 14,000 yards (12,800 m)

Mount/Turret Data

Designation Single Barbette Mount
   Atlanta (2): Mark 1

Single "Half-turret" 1
   Chicago (4): Mark 2

Weight N/A
Elevation -5 / +20 degrees
Elevation Rate N/A
Train about +150 / -150 degrees
Train Rate N/A
Gun recoil N/A
Loading angle N/A
  • ^The Mark 2 "half-turret" was a cylindrical shield with a top but no back.
  • These mounts were steam powered.

Additional Pictures


"US Naval Weapons" and "US Cruisers: An Illustrated Design History" both by Norman Friedman
"Ordnance and Gunnery, A Text-book Prepared for the Use of the Midshipmen of the United States Naval Academy" by Officers of the U.S. Navy (1910)

Page History

27 August 2006 - Benchmark
24 March 2010 - Added note about guns from Boston
29 July 2016 - Converted to HTML 5 format
07 July 2018 - Added photograph of gun being assembled
06 June 2019 - Added photograph of guns at Hamlin Park
23 October 2020 - Added ammunition data