United States of America
8"/35 (20.3 cm) Marks 3 and 4
8"/40 (20.3 cm) Mark 5
Updated 04 June 2009
The late 1800s saw the development of slower-burning brown or "cocoa" powder.  This propellant allowed longer, higher muzzle velocity weapons to be developed, but wasted much of its energy producing clouds of thick smoke.  Experience gained with the earlier 8"/30 (20.3 cm) guns led to a simpler construction for these longer guns.

During the Battle of Manila Bay in 1898, USS Olympia fired an 8" (20.3 cm) shell from one of her 8"/35 (20.3 cm) guns that struck the Spanish flagship Reina Christina "squarely in the stern and drove through the length of the ship, rending every obstruction, wrecking the aft boiler, and blowing open the deck in its explosion.  This one shell proved the flagship's fate" - Ivan Musicant in "U.S. Armored Cruisers."

The 8"/35 (20.3 cm) Mark 3 gun barrels intended for Brooklyn (ACR-3) and Iowa (B-4) were initially rejected by the Bureau of Ordnance, as they were honeycombed with small "sand splits," a result of the excessive amounts of clay and slag used in the gun metal.  However, after a delay of two years, they were accepted at a reduced cost.  Three of these guns on Iowa subsequently blew off their muzzles during a gunnery exercise in 1904 - see photograph on additional pictures page.

The Mark 3 had 11 hoops.  One gun, designated Mod 3, was lengthened to 40 calibers.  The Mark 4 was similar but with the trunnion hoop and elevating band removed, with the threads formerly under the trunnion hoop being continued to the rear of the gun, which allowed it to be screwed into the sleeve of a two-gun turret mount.  One gun, designated Mod 10, was cut down to 23 calibers for experimental work with high-explosive shells.

Mark 5 was a new 40 caliber design intended for armored cruisers and battleship secondaries.  Unfortunately, the Mark 5 proved to be unable to handle the transition from black to brown powder, as the new propellant burned more slowly, which allowed pressure to build up to unsafe levels as the projectile traveled down the bore.  This problem was illustrated when USS Colorado (ACR-7) blew off the muzzle of one of her 8" (20.3 cm) guns during a gunnery exercise off Chefoo, Shantung, on 22 June 1907.  All Mark 5 guns were subsequently removed from service, rehooped to the muzzle and then placed in reserve.  Most of these ships were then rearmed with the stronger 8"/45 (20.3 cm) Mark 6.
WNUS_8-35_mk3_Indiana_pic.jpg

8"/35 (20.3 cm) mount on USS Indiana B-3 sometime in the 1890s
U.S. Naval Historical Center Photograph # NH 93856
.
Click here for additional pictures
.
.
Gun Characteristics
.
Designation 8"/35 (20.3 cm) Marks 3 and 4
8"/40 (20.3 cm) Mark 5
Ship Class Used On 8"/35 (20.3 cm)
   Battleships:  Indiana (B-1), Iowa (B-4) and Kearsage (B-5)
   Cruisers:  New York (ACR-2), Brooklyn (ACR-3), Charleston (C-2), Baltimore (C-3) and Olympia (C-6) classes

8"/40 (20.3 cm)
   Pennsylvania (ACR-4) and Columbia (C-12) classes
Date Of Design about 1890
Date In Service Mark 3:  1889
Mark 5:  1894
Gun Weight Mark 3:  29,400 lbs. (13,336 kg) without breech block
Others:  N/A
Gun Length N/A
Bore Length Mark 3 and 4:  280 in (7.112 m)
Mark 5:  320 in (8.128 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist Mark 3 and Mark 4:  Increasing RH 0 to 1 in 25
Mark 5:  N/A
Chamber Volume N/A
Rate Of Fire
(see Note 1)		 1890s:  0.5 to 0.8 rounds per minute
1900s:  2 - 2.8 rounds per minute
Notes:

1) In 1897 the 8"/35 (20.3 cm) gun was timed at one shot every 120 seconds (2 minutes).  This was greatly improved by more careful loading practices and better training so that by a decade later a rate of 30 seconds or less was achieved.  For example, USS New York as commissioned in 1893 was timed at one round every 77 seconds.  At the annual fleet exercise in 1905, one of her gun crews fired 2.8 rounds per minute and was able to score seven hits in 2.5 minutes.

2) Early guns used percussion firing.  Later guns used a Fletcher Breech (down-swinging carrier type) which allowed electrical firing.
.
Ammunition
.
Type Bag
Projectile Types and Weights AP - 260 lbs. (118 kg)
Common - 260 lbs. (118 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 43.8 lbs. (19.9 kg)
Muzzle Velocity 8"/35 (20.3 cm):  2,100 fps (640 mps)
8"/40 (20.3 cm):  2,500 fps (762 mps)
Working Pressure N/A
Approximate Barrel Life N/A
Ammunition stowage per gun Indiana:  75 rounds
Kearsage and Brooklyn:  125 rounds
Others:  N/A
.
Range
.
Elevation With 260 lbs. (118 kg) AP Shell
Range @ 20.1 degrees
Muzzle velocity = 2,100 fps (640 mps)		 16,000 yards (14,630 m)
.
Armor Penetration With 260 lbs. (118 kg) Shell
Data for 8"/35 (20.3 cm) Mark 3
.
Range
Side Armor
Deck Armor
6,000 yards (5,490 m)
5.6" (142 mm)
---
9,000 yards (8,230 m)
4.1" (104 mm)
---
12,000 yards (10,920 m)
2.9" (74 mm)
---
This data is from "Elements of US Naval Guns" of 1918.  It is corrected for angle of fall and may also refer to harder armor than used for the 1905 data.
.
Mount / Turret Data
.
Designation Single center-pivots
   New York (2), Charleston (2), Baltimore (2), and Columbia (1):  Mark 3 and Mark 4

Twin Turrets
   New York (2):  Mark 5
   Olympia (2):  Mark 6
   Indiana (4):  Mark 7
   Brooklyn (4) and Iowa (4):  Mark 8

Dual-Caliber Turret
   Kearsage (2):  Mark 9 (superimposed turret)
Weight  N/A
Elevation Marks 3 and 4:  -5 / +20 degrees
Marks 5 and 6:  -4 / +13 degrees
Mark 7:  -7 / +14 degrees
Mark 8:  -7 / +14 degrees
Mark 9:  -7 / +14 degrees
Elevation Rate N/A
Train
(see Notes 4 and 6)		 Bow and Stern Mountings:  - 150 / +150 degrees
New York Amidships Mountings:  140 degrees
Brooklyn Amidships Mountings:  180 degrees
Train Rate N/A
Gun recoil N/A
Loading angle Marks 3 and 4:  Any angle
Marks 5, 6 and 7:  0 degrees
Others:  N/A
Notes:

1) None of the turrets were balanced, which means that training them abeam created a list.

2) The Mark 4 had a single-casting slide.  Mark 5 used gravity return, possible that so did Mark 6.  Mark 5 used steam-powered hydraulic pumps for elevation and training, with manual backup gear.  Ammunition hoists were electrically driven with both steam and manual backup gear.

3) Mark 7 and Mark 8 used the "grass-hopper" counter recoil system whereby a spring box, located under the gun pit, was connected via two heavy, pivoted arms to the gun yoke.  See 10"/40 (25.4 cm) datapage for a sketch.

4) The amidships mountings on USS New York had a theoretical arc of 180 degrees, thus allowing axial fire, but in practice the firing arcs were limited to 140 degrees in order to minimize the blast effect on the deck and superstructure.

5) The four Mark 8 turrets on USS Brooklyn were split into two steam powered and two electrical powered mountings in order to evaluate the advantages of each system.  General Electric installed a modified Ward-Leonard system into the two electrically powered mountings.  Tests on 3 March 1896 proved the electric turrets to be far superior to the steam-powered turrets in terms of smoothness and reliability and this system was adopted for future construction.

6) USS Brooklyn was the only US ship to be designed with her turrets in a lozenge arrangement.  Thanks to the extreme tumble home of the hull, the wing turrets could fire directly forward and aft.  She put this to good use at the Battle of Santiago, where her captain, Francis Cook, reported that "our tumbling-in sides enabled us to maintain continual fire while turning."

7) During modernizations in 1905, USS New York and the Pennsylvania class were rearmed with 8"/45 (20.3 cm) Mark 6 guns.
.
Data from
"U.S. Battleships:  An Illustrated Design History" and "US Naval Weapons" both by Norman Friedman
"U.S. Armored Cruisers:  A Design and Operational History" by Ivan Musicant
"Battleships" by Paul Stillwell
Page History

18 September 2008 - Benchmark
06 January 2009 - Added two pictures of USS Maryland on additional pictures page
04 June 2009 - Added information on Common projectiles, corrected typographical error