United States of America
16"/45 (40.6 cm) Mark 5 and Mark 8
Updated 07 February 2008
Used only on the USS Colorado (BB-45) class battleships, these guns were reconstructed from the original 16"/45 (40.6 cm) Mark 1 weapons during the 1930s modernization of the battlefleet.  The major difference from the Mark 1 gun was the redesign of the chamber to permit larger charges, a new liner with heavier taper carbon steel, liner-locking ring and locking collar.  A later version, the Mark 8, was similar except that rifling was uniform and the bore was chromium plated for increased life.

These ships could not fire the "super-heavy" 2,700 pound (1,224.7 kg) AP Mark 8 projectile, as that shell was too heavy and too long for their handling equipment.  However, in the late 1930s they were given the 2,240 lbs. (1,016 kg) AP Mark 5, which was a heavier projectile with better armor piercing capability than the 2,110 lbs. (957.1 kg) AP Mark 3 that was originally issued.  By 1942, these ships were also issued an HC projectile.

The data that follows is specifically for the 16"/45 (40.6 cm) Mark 5 Mod 1 unless otherwise noted.
WNUS_16-45_mk5_Colorado_Okinawa_pic.jpg

USS Colorado BB-45 bombarding Okinawa 29 March 1945
U.S. Naval Historical Center Photograph # 80-G-316831
WNUS_16-45_mk5_West_Virginia_pic.jpg

USS West Virginia BB-48 in July 1944 following reconstruction
Note that twin 5"/38 (12.7 cm) DP mounts have replaced the previous mixed secondaries
U.S. Naval Historical Center Photograph # 19-N-68376
WNUS_16-45_mk5_Colorado_color_pic.jpg

A rare color photograph of USS Colorado BB-45 circa November 1943
Note that the after cage mast has been cut down and made into an AA platform
U.S. Naval Historical Center Photograph # K-13670
WNUS_16-45_mk5_Colorado_pic.jpg

USS Colorado BB-45 in 1943
This picture may have been taken at the same time as the one above
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Gun Characteristics
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Designation 16"/45 (40.6 cm) Mark 5 and Mark 8
Ship Class Used On Colorado (BB-45) Class
Date Of Design about 1935
Date In Service about 1938
Gun Weight 235,796 lbs. (106,959 kg) (including breech) 
230,948 lbs. (104,757 kg) (without breech)
Gun Length oa 736.0 in (18.694 m)
Bore Length 720.0 in (18.288 m)
Rifling Length 616.9 in (15.668 m)
Grooves 96
Lands N/A
Twist Mark 5:  Increasing RH 1 in 50 to 1 in 32
Mark 8:  Uniform RH 1 in 25
Chamber Volume 23,506 in3 (385.3 dm3)
Rate Of Fire
(see Note 2)		 about 1.5 rounds per minute
Notes:

1) The bore of the Mark 8 was chromium plated for a distance of 625 inches (15.875 m) from the muzzle.

2) During the Battle of Surigao Strait on 25 October 1944, West Virginia fired thirteen full salvos under full radar control using the after Mark 8 Mod 2 radar.  Rapid salvo fire was used after the second salvo and the average time between salvos was 41 seconds.  Opening gun range was 22,400 yards (20,480 m) and average range was 20,880 yards (19,090 m).  The first salvo fired was a straddle with hits being observed and all subsequent full salvos were straddles.  The right gun of turret 1 missed 3 salvos and the right gun of turret 3 missed 7 salvos.  These missed salvos were primarily due to shell hoist casualties in those two mountings.  From her gunnery report:

"A total of 89 A.P. and 4 H.C. projectiles were fired, all with service charges.  Due to shell hoist casualties in turrets 1 and 3 and the lack of supply in turret 4, the Gun Captains loaded H.C. projectiles, which were available on the table, when there were no A.P. available.  Turret 3 fired one H.C. on the 6th salvo.  Turret 1 fired one H.C. on each of the 9th and 10th salvos.  Turret 4 fired one H.C. on the 15th salvo.  Turret 2 was slow on loading after the 12th salvo and missed the 13th salvo.  Turret 4 had two projectiles rammed at cease firing and was ordered to continue the load.  The left gun misfired on the 15th salvo necessitating a 16th salvo."
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Ammunition
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Type Bag
Projectile Types and Weights AP Mark 5 Mods 1 to 6 - 2,240 lbs. (1,016 kg)
HC Mark 13 Mods 0 to 6 - 1,900 lbs. (862 kg)
HC Mark 14 Mod 0 - 1,900 lbs. (862 kg)
Bursting Charge AP Mark 5 - 33.6 lbs. (15.2 kg)
HC Mark 13 - 153.6 lbs. (69.67 kg)
HC Mark 14 - 153.6 lbs. (69.67 kg)
Projectile Length AP Mark 5 - 64.0 in (162.6 cm)
HC Mark 13 - 64.0 in (162.6 cm)
HC Mark 14 - 64.0 in (162.6 cm)
Propellant Charge Full Charge - 545.0 lbs. (247.2 kg) SPD

Reduced Charge - 295.0 lbs. (133.8 kg) SPD or SPDN
Reduced Flashless Charge - 315.0 lbs. (142.9 kg) SPCG
Muzzle Velocity Full Charge - New Gun
   AP - 2,520 fps (768 mps)
   HC - 2,635 fps (803 mps)

Reduced Charge - New Gun
   AP - 1,935 fps (590 mps)
   HC - 2,075 fps (632 mps)
Working Pressure 18.0 tons/in2 (2,835 kg/cm2)
Approximate Barrel Life Mark 5:  320 rounds
Mark 8:  395 rounds
Ammunition stowage per gun
(see Note 4)		 100 rounds
Notes:

1) The AP Mark 5 was a major change to a hard-capped, sheath-hardened AP projectile that could penetrate caliber-thickness face-hardened armor at 30 to 40 degree obliquity (this was its test specification).  It gained most of its extra weight by reducing the filler to only 1.5% of its total weight and by using a thicker, wider, high-hardness AP cap.  These projectiles with a different fuze adapter and base fuze were issued to the U.S. Army Coast Defense Command as the AP Mark 12.  These Mark 5 and Mark 12 projectiles had a very blunt - though still pointed - body nose under the AP cap to improve their high-obliquity penetration of medium-thickness homogeneous deck and turret roof armor.  The AP Mark 5 projectiles were designed to be used in long-range gun actions against Japanese ships ("Plan Orange") and for that reason they were to be fired at relatively low muzzle velocities and high gun elevations.  These conditions would result in a steeper angle of fall in order to enhance their deck armor penetration capabilities.

2) For information on the HC Mark 13 and HC Mark 14, see the 16"/50 (40.6 cm) Mark 7 data page.

3) The propellant charge was in five bags.

4) Following her rebuild after Pearl Harbor, USS West Virginia carried 90 rounds per gun.

5) After 1941 AP rounds had a nominal 1.5 lbs. (0.68 kg) dye bag added but this was allowed to be as large as 3.0 lbs. (1.36 kg) in order to bring underweight projectiles up to standard.  These ships were assigned the following dye colors:

   Colorado - Orange
   Maryland - Blue (?)
   West Virginia - No dye (White)

6) Bourrelet diameter was 15.977 inches (40.06 cm).
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Range
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Elevation
 With 2,240 lbs. (1,016 kg) AP Mark 5
MV = 2,520 fps (768 mps)
Striking Velocity
Angle of Fall
2.9 degrees
6,000 yards (5,490 m)
2,200 fps (671 mps)
3.1
5.1 degrees
10,000 yards (9,140 m)
2,007 fps (612 mps)
5.9
9.1 degrees
16,000 yards (14,630 m)
1,758 fps (536 mps)
11.5
12.3 degrees
20,000 yards (18,290 m)
1,629 fps (497 mps)
16.3
15.0 degrees
23,000 yards (21,030 m)
---
---
18.0 degrees
26,000 yards (23,770 m)
1,507 fps (459 mps)
25.1
20.0 degrees
27,900 yards (25,510 m)
---
---
22.7 degrees
30,000 yards (27,430 m)
1,472 fps (449 mps)
31.7
25.0 degrees
31,900 yards (29,170 m)
---
---
30.0 degrees
(maximum elevation of turret)
35,000 yards (32,000 m)
1,486 fps (453 mps)
---
31.7 degrees
36,000 yards (32,920 m)
1,496 fps (456 mps)
42.4
35.0 degrees
37,500 yards (34,290 m)
---
---
40.0 degrees
39,300 yards (35,940 m)
---
---
45.0 degrees
40,200 yards (36,760 m)
---
---
Note:  Time of flight for AP Shell with MV = 2,520 fps (768 mps)
   10,000 yards (9,140 m): 13.4 seconds
   20,000 yards (18,290 m):  30.6 seconds
   30,000 yards (27,430 m):  53.1 seconds
   36,000 yards (32,920 m):  70.6 seconds
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Elevation
With 1,900 lbs. (862 kg) HC Mark 13 Shell
MV = 2,635 fps (803 mps)
30 degrees
(maximum elevation of turret)
34,900 yards (31,910 m)
45 degrees
40,180 yards (36,730 m)
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Armor Penetration with 2,240 lbs. (1,016.06 kg) AP Mark 5
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Range
Side Armor
Deck Armor
0 yards (0 m)
29.68" (754 mm)
---
5,000 yards (4,570 m)
26.0" (661 mm)
---
10,000 yards (9,140 m)
22.5" (572 mm)
---
16,800 yards (15,360 m)
18.0" (457 mm)
---
20,300 yards (18,560 m)
16.0" (406 mm)
2.0" (51 mm)
22,000 yards (20,120 m)
---
4.0" (102 mm)
24,500 yards (22,400 m)
14.0" (356 mm)
---
28,200 yards (25,790 m)
---
6.0" (152 mm)
29,500 yards (26,970 m)
12.0" (305 mm)
---
34,500 yards (31,550 m)
---
8.0" (203 mm)
35,500 yards (32,460 m)
10.0" (254 mm)
---
38,500 yards (35,200 m)
---
10.0" (254 mm)
Note:  These figures are taken from USN armor penetration curves issued in 1942.
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Range
Side Armor
Deck Armor
Striking Velocity
Angle of Fall
0 yards (0 m)
29.68" (754 mm)
---
2,600 fps (768 mps)
0
5,000 yards (4,572 m)
26.04" (661 mm)
0.75"  (19 mm)
2,253 fps (687 mps)
3.03
10,000 yards (9,144 m)
22.53" (572 mm)
1.52"  (39 mm)
2,007 fps (612 mps)
5.92
15,000 yards (13,716 m)
19.22" (488 mm)
2.51"  (64 mm)
1,796 fps (547 mps)
10.5
20,000 yards (18,288 m)
16.24" (412 mm)
3.56"  (90 mm)
1,629 fps (497 mps)
16.33
25,000 yards (22,860 m)
13.74" (349 mm)
4.78" (121 mm)
1,522 fps (464 mps)
23.55
30,000 yards (27,432 m)
11.68" (297 mm)
6.24" (158 mm)
1,472 fps (449 mps)
31.68
35,000 yards (32,004 m)
10.02" (254 mm)
8.15" (207 mm)
1,486 fps (453 mps)
49.47
40,000 yards (36,576 m)
8.27" (210 mm)
11.39" (289 mm)
1,586 fps (483 mps)
51.86
Note:  This data is from "Battleships:  United States Battleships 1935-1992" and is based upon the USN Empirical Armor Penetration Formula.  These values are in substantial agreement with armor penetration curves published in 1942.
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Mount / Turret Data
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Designation Two-gun turrets
   Colorado (4)
Weight 880 - 920 tons (894.08 - 934.72 mt)
Elevation -4 / +30 degrees
Rate of Elevation about 8 degrees per second
Train 300 max 280 min degrees
Rate of Train about 2 degrees per second
Gun Recoil 48 in (1.22 m)
Loading Angle +1 degree
Notes:

1) West Virginia was fitted with RPC when rebuilt after Pearl Harbor.  Colorado and Maryland were scheduled to receive RPC, but this was cancelled at the end of World War II.

2) See 16"/45 (40.6 cm) Mark 1 data page for other information about these mountings.
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Data from
"Naval Weapons of World War Two" by John Campbell
"U.S. Battleships:  An Illustrated Design History" and "US Naval Weapons" both by Norman Friedman
"Battleships:  United States Battleships, 1935-1992" by W.H. Garzke, Jr. and R.O. Dulin, Jr.
"US Warships of World War II" by Paul Silverstone
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Navy Pages by Gene Slover
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"U.S. Explosive Ordnance:  Ordnance Pamphlet 1664 - May 1947" by Department of the Navy
"USS Massachusetts 1945 Gunnery Doctrine" a USN BuOrd Publication
"Operational Experience of Fast Battleships:  World War II, Korea and Vietnam" a U.S. Naval Historical Center Publication edited by John C. Reilly, Jr.
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Special help by Leo Fischer, Nathan Okun and Ed Jackson
Off-site Resources

For a description of these guns in action at Leyte Gulf, see this link to HyperWar USS West Virginia (BB-48) Action Report for Surigao Strait