Description

These guns were used as battleship and cruiser secondary weapons and as the main guns on Gunboats. Mark 1 Mod 0 used bag ammunition, all others fired fixed ammunition. Earlier guns were of layered built-up construction while later ones were hooped to the muzzle. All of these guns used side-swinging, carrier-type Dashiell breech blocks and had similar performance.

Britain tried to obtain some of these guns to arm DAMS during World War I and even assigned a Mark number to them, but none could be spared from the USN's building programs.

Gun Characteristics

Designation USN: 4"/40 (10.2 cm) Marks 1, 3, 4, 5 and 6
British: 4"/40 (10.2 cm) QF Mark XI
Ship Class Used On Iowa (B-4), Puritan (M-1), Columbia (C-12) and New York (ACR-2) classes
Gunboats: Machias (PG-5), Nashville (PG-7), Wilmington (PG-8), Helena (PG-9), Annapolis (PG-10), Wheeling (PG-14) and Topeka (PG-35)
Date Of Design About 1892
Date In Service 1897
Gun Weight Mark 1: 3,388 lbs. (1,537 kg) without breech
Mark 2: 3,398 lbs. (1,541 kg) without breech
Mark 3: N/A
Mark 4: 3,160 lbs. (1,433 kg) with breech
Mark 5: 3,100 lbs. (1,406 kg) with breech
Mark 6: 3,529 lbs. (1,600 kg) with breech
Gun Length oa N/A
Bore Length 160.0 in (4.064 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist Increasing RH 0 to 1 in 25
Chamber Volume N/A
Rate Of Fire 8 - 9 rounds per minute 1
  • ^The ROF figure given above was typical, but well-trained crews could fire as fast as fifteen rounds per minute. During the 1905 target shoot off Culebra, Puerto Rico, one of USS New York (ACR-2) gun crews fired fourteen rounds in one minute and scored eleven hits.

Ammunition

Type Mark 1: Bag
All others: Fixed
Weight of Complete Round N/A
Projectile Types and Weights AP: 33 lbs. (15 kg)
Common: 33 lbs. (15 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 14.0 lbs. (6.4 kg) Brown Powder
4.85 lbs. (2.2 kg) SP or SPD
Muzzle Velocity 2,000 fps (610 mps)
Working Pressure Mark 1: 15.25 tons/in2 (2,400 kg/cm2)
Others: 15.5 tons/in2 (2,440 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun N/A

Range

Range with 33 lbs. (15 kg) HE
Elevation Distance
31.2 degrees 11,500 yards (10,520 m)

Armor Penetration

Armor Penetration with 33 lbs. (15 kg) AP
Range Side Armor Deck Armor
3,000 yards (2,750 m) 1.7" (43 mm) ---
6,000 yards (5,490 m) 1.2" (30 mm) ---

Data from "U.S. Armored Cruisers" and is for KNC armor.

Mount/Turret Data

Designation Single Mountings
   Central Pivot: Marks 2 and 3 1a
   Pedestal: Marks 4, 7 and 9

   Iowa (6), Puritan (6), Columbia (8) and New York (12) 2a
   Machias (8), Helena (8), Nashville (8), Wilmington (8), Annapolis (6), Wheeling (6) and Topeka (6)
Weight Mark 2: 9,248 lbs. (4,195 kg)
Mark 3: 9,075 lbs. (4,116 kg)
Marks 4 to 7: Between 7,700 - 8,600 lbs. (2,493 - 3,901 kg)
Elevation about -15 / +20 degrees
Elevation Rate Manual operation, only
Train about +150 / -150 degrees
Train Rate Manual operation, only
Gun recoil N/A
  • ^The Mark 3 differed from the Mark 2 in having no directing bar, training was by handwheel with sights on the slide and being non-recoiling. Many Mark 2 mounts were later converted to the Mark 3 standard.
  • ^Cruisers had electrically-powered continuous chain ammunition hoists.

Additional Pictures

Sources

"British Naval Guns 1880-1945 No 18" article by John Campbell in "Warship Volume X"
"U.S. Battleships: An Illustrated Design History," "U.S. Cruisers: An Illustrated Design History" and "US Naval Weapons" all by Norman Friedman
"U.S. Armored Cruisers: A Design and Operational History" by Ivan Musicant
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"U.S. Explosive Ordnance: Ordnance Pamphlet 1664 - May 1947" by Department of the Navy
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Tony DiGiulian's personal files

Page History

12 February 2008 - Benchmark
12 February 2012 - Updated to latest template and added mounting information
05 February 2023 - Converted to HTML 5 format and added photograph of guns from Puritan and Topeka
16 June 2023 - Added photographs of Dashiell Breech mechanism