In 1890 the Policy Board called for a variety of large caliber weapons, all the way up to 16" (40.3 cm) although this last caliber was beyond the technology of the day. A lighter-weight heavy weapon was also desired for long-range battleships and coastal monitors, which led to the development of the 12"/35 (30.5 cm).
The Mark 1 was fitted to the Second-Class Battleship Texas and some monitors, the very similar Mark 2 was fitted to the USS Iowa B-4.
The Mark 1 consisted of A tube, jacket, ten hoops and a locking ring, all constructed of gun steel. The original Mod 0 was hooped from muzzle to six inches (15.24 cm) before the breech. Mod 1 was hooped all the way to the breech. The Mark 2 construction was A tube, seven hoops and a locking ring. Hooped similiarly to Mark 1 Mod 1 and designed to have the same external dimensions as that weapon. Mark 2 Mod 1 and Mod 2 were given new nickel-steel liners and had the outer B hoops replaced with new gun-steel ones with the finished external dimensions being unchanged.
In 1908 AP projectiles were fitted with a more streamlined ballistic cap of 7crh which improved their long-range penetration ability.
Background note: The gunpowder propellants used for most of the 19th century burned very quickly, giving the projectiles a short, sharp kick. For guns using these propellants, the longer the gunbarrel, the slower the muzzle velocity due to friction after the propellant had already finished combustion. This is why heavy guns of the black-powder era had such short barrels, some only 20 calibers long. The late 1800s saw the development of brown or cocoa powders which burned more slowly, allowing guns like the 12"/35 (30.5 cm) to have longer barrels with higher muzzle velocities, but these propellants also wasted much of their energy in producing thick, heavy smoke. Around the turn of the century nitrocellulose propellants (known in the USN as "Smokeless Powder" or SP) were introduced and these led to much longer weapons and higher muzzle velocities. See the Naval Technical Board essay "Naval Propellants - A Brief Overview" for additional information.
|Designation||12"/35 (33 cm) Mark 1 and Mark 2|
|Ship Class Used On||Mark 1: Texas (1896), Puritan (M-1)
and Monterey (M-6)
Mark 2: Iowa (B-4)
|Date Of Design||N/A|
|Date In Service||1896|
|Gun Weight||102,550 lbs. (46,516 kg) (including breech)
100,800 lbs. (45,722 kg) (without breech)
|Gun Length oa||441 in (11.0201 m)|
|Bore Length||425 in (10.795 m)|
|Twist||Increasing RH 0 to 1 in 25|
|Rate Of Fire||about 1 round per minute|
|Projectile Types and Weights||AP - 870 lbs. (394.6 kg)
Common - 870 lbs. (394.6 kg)
|Propellant Charge||160 lbs. (72.6 kg)|
|Muzzle Velocity||2,100 fps (640 mps)|
|Working Pressure||15.5 tons/in2 (2,440 kg/cm2)|
|Approximate Barrel Life||N/A|
|Ammunition stowage per gun||Texas: 80 rounds
Iowa: 60 rounds
Texas (2): Mark 2
|Weight||Mark 1: N/A
Mark 2: N/A
Mark 3: 448 tons (455 mt)
|Elevation||Mark 1: -3 / +15 degrees
Mark 2: -5 / +15 degrees
Mark 3: -3 / +14 degrees
|Rate of Elevation||N/A|
|Train||about -150 / +150 degrees|
|Rate of Train||N/A|
|Loading Angle||Mark 1: +9.5 degrees
Mark 2: 0 degrees
Mark 3: +3 degrees
- The Mark 2 turrets on Texas originally could only load at 0 degrees train angle as well as at 0 degrees elevation. This because the hydraulic rammers for these guns were located outside of the turrets in the fixed structure and so did not rotate with the turrets. Shortly before the start of the Spanish-American War, internal telescoping rammers were fitted inside of the turrets which then allowed the guns to be loaded at any angle of train.
- The Mark 3 was the first balanced rotating turret in USN service. It could be loaded either by hand or with an electric rammer.
- The monitor Monterey was unusual in that she had a twin 12"/35 (30.5 cm) turret forward and a twin 10"/30 (25.4 cm) turret aft.