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Photo provided by Mr. Kittel
| A series of 3"/50
(7.62 cm) AA guns dating back to the early 1900s. Successive marks
were improved designs. This was the only dual-purpose
gun in the USN's inventory and widely used up to the mid-1930s, but then
replaced on larger ships by 5"/38 (12.7 cm) and 40 mm mountings,
although the Battleships New York and Arkansas still had them as late as
1943. USS Texas retained the 3"/50 through out WWII.
Used on many smaller ships such as Destroyer Escorts and
Submarines during WWII.
These guns had
limited effectiveness in either role, as they were not power operated
and so could not be fitted for RPC. However, the invention of the
VT fuse and the Mark 51 director system greatly improved their
effectiveness and gave the later marks of this weapon a new lease on
life. In the fall of 1945, CinCPac considered a 3"/50 (7.62
cm) with director control and VT ammunition to be superior to a twin 40
mm mount and at least equivalent to a quad 40 mm mount.
Marks 10, 17 and 20 were built up guns
with A tube, jacket and hoop. Mark 18 was made from copper-nickel
alloy for wet mountings with A tube, jacket, screwed and shrunk breech
housing. Marks 21 and 22 were very similar apart from a collar on
the chase in Mark 22, which was intended a concentric counter-recoil
spring fitted only in Mark 24 wartime mountings but used in post-war
automatic mountings. Both had chromium plated bores and had
autofretted monoblco barrels secured to the breech housings by bayonet
joints. All used a semi-automatic vertical sliding breech block.
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Gun Characteristics
| Designation |
3"/50 (7.62 cm)
Marks 10, 17, 18, 20, 21 and 22 |
| Ship Class Used On |
Many ships 1910 through
1945 |
| Date Of Design |
1908 to 1944 |
| Date In Service |
1910 to 1944 |
| Gun Weight |
1,760 lbs. (798 kg) |
| Gun Length oa |
159.7 in (4.055 m) |
| Bore Length |
150.3 in (3.816 m) |
| Number Of Grooves |
24 |
| Length Of Rifling |
126.1 in (3.204 m) |
| Chamber Volume |
217 in3 (3.56
dm3) |
| Rate Of Fire |
15 - 20 rounds per minute |
Ammunition
| Type |
Fixed |
| Weight of Complete Round |
24 lbs. (10.9 kg) |
| Projectile Types and
Weights |
HE - 15 lbs. (6.8 kg) |
| Bursting Charge |
NA |
| Projectile Length |
N/A |
| Propellant Container Type
and Weight |
Cartridge - 9 lbs. (4.1
kg) |
| Propellant Charge |
3.7 lbs. (1.68 kg) |
| Muzzle Velocity |
HE - 2,700 fps (823 mps) |
| Working Pressure |
17.0 tons/in2
(2,680 kg/cm2) |
| Approximate Barrel Life |
4,300 rounds |
Range
| Elevation |
Using 15 lbs. (6.8 kg)
HE Shell |
| Range @ 45 degrees |
14,600 yards (13,350 m) |
| AA Ceiling |
30,400 feet (9,266 m) |
Mount / Turret Data
| Designation |
Wet mountings
(submarines)
For Mark 17 guns: Mark
11
For Mark 18 guns: Mark
18
For Mark 21 guns: Mark
21
Dry Mountings
For Mark 10 guns: Mark
11
For Mark 20 guns: Mark
20
For Mark 21 and 22 guns:
Mark 22 and 24
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| Weight |
3.0 to 4.2 tons (3.1 to
4.3 mt) |
| Elevation |
-15 / +85 degrees |
| Elevation Rate |
Manually operated, only |
| Train |
360 degrees |
| Train Rate |
Manually operated, only |
| Gun recoil |
N/A |
Data from:
www.NavWeaps.com
"US Naval Weapons" by Norman Friedman
"Naval Weapons of WWII" by John Campbell
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