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.
|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|
|Bore Length||240 in (6.096m)|
|Twist||Increasing RH 1 in 180 to 1 in 30 at the muzzle|
|Rate Of Fire||about 0.5 - 1 round per minute|
|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
|Propellant Charge||49.6 lbs. (22.5 kg)|
|Muzzle Velocity||2,000 fps (610 mps)|
|Approximate Barrel Life||N/A|
|Ammunition stowage per gun||N/A|
|20 degrees||about 14,000 yards (12,800 m)|
|Designation||Single Barbette Mount
Atlanta (2): Mark 1
Single "Half-turret" 1
|Elevation||-5 / +20 degrees|
|Train||about +150 / -150 degrees|
- ^The Mark 2 "half-turret" was a cylindrical shield with a top but no back.
- These mounts were steam powered.
"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)
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