Description

The Mark 1 was a simply constructed weapon used as a boat gun. Monobloc construction with a Fletcher breech mechanism and used a hydraulic recoil piston screwed directly onto the gun.

The Mark 1 Mod 1 was of similar construction but used a solid lug for the piston rod. The barrel slid in the cradle and had two keys on the horizontal line through its center. Used a modified Fletcher breech mechanism.

Gun Characteristics

Designation 3"/21 (7.62 cm) Mark 1
Ship Class Used On N/A
Date Of Design About 1890
Date In Service About 1890
Gun Weight 384 lbs. (174 kg)
Gun Length 69.6 in (1.768 m)
Bore Length 64.3 in (1.633 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist RH 1 in 29.89
Chamber Volume N/A
Rate Of Fire about 8 - 9 rounds per minute

Ammunition

Type Bag
Projectile Types and Weights HE: 13 lbs. (5.9 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity 1,150 fps (351 mps)
Working Pressure 9.5 tons/in2 (1,500 kg/cm2)
Approximate Barrel Life N/A

Range

Range with 13 lbs. (5.9 kg) Shell
Elevation Range
19.5 degrees 5,000 yards (4,570 m)

Mount/Turret Data

Simple carriage mounting. Maximum elevation was slightly greater than 19.5 degrees.

Sources

"US Naval Weapons" by Norman Friedman
"A Treatise on Rifling of Guns" by Carl F. Jeansén
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"United States Naval Guns: Their Marks and Modifications" Ordnance Pamphlet No. 127, December 1916, Second Revision June 1924
Gene Slover's Navy Pages
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Special help from Leo Fischer

Page History

03 December 2006 - Benchmark
07 August 2017 - Converted to HTML 5 format