Description

Designed to arm commerce-raiding heavy cruisers and for coastal defense, a single prototype was built but this weapon did not enter service use.

Actual barrel length was 55.74 calibers. Actual bore diameter was 30.50 cm (12.008").

Gun Characteristics

Designation 30.5 cm/56 (12") SK C/39
Ship Class Used On Planned
Date Of Design 1939
Date In Service Not in service
Gun Weight 147,267 lbs. (66,800 kg)
Gun Length oa 669.29 in (17.000 m)
Bore Length 626.97 in (15.925 m)
Rifling Length 500.98 in (12.725 m)
Grooves (72) 0.142 deep x 0.319 (breech) - 0.3425 in (muzzle) (3.6 deep x 8.11 to 8.70 mm)
Lands 0.205 (breech) to 0.1815 in (muzzle) (5.20 to 4.61 mm)
Twist Increasing RH 1 in 32.6 to 1 in 27.6
Chamber Volume 17.697 in3 (290 dm3)
Rate Of Fire 2 - 3 rounds per minute

Ammunition

Type Cartridge - Bag
Projectile Types and Weight 1 2 APC L/4,9 - 915 lbs. (415 kg)
HE L/5 base fuze - 915 lbs. (415 kg)
HE L/4,8 nose fuze - 915 lbs. (415 kg)
Coastal HE L/3,6 base and nose fuze - 551 lbs. (250 kg) 3
Bursting Charge APC L/4,9 - N/A
HE L/5 base fuze - N/A
HE L/4,8 nose fuze - N/A
Coastal HE L/3,6 base and nose fuze - 32.0 lbs. (14.5 kg)
Projectile Length APC L/4,9 - about 58.8 in (149.5 cm)
HE L/5 base fuze - about 60.0 in (152.5 cm)
HE L/4,8 nose fuze - about 57.6 in (146.5 cm)
Coastal HE L/3,6 base and nose fuze - 55.1 in (140 cm)
Propellant Charge 379 lbs. (172 kg) RP C/40N
Muzzle Velocity APC, HE base fuse and HE nose fuze - 2,880 fps (865 mps)
Coastal HE L/3,6 base and nose fuze - 3,675 fps (1,120 mps)
Working Pressure 19.0 tons/in2 (3,000 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
  • ^
    Actual Projectile designations
    APC L/4,9 30,5 cm Psgr. L/4,9 (m.Hb)
    HE L/5 base fuze 30,5 cm Spgr. L/5 Bdz. (m.Hb)
    HE L/4,8 nose fuze 30,5 cm Spgr. L/4,8 Kz. (m.Hb)
    Coastal HE L/3,6 base and nose fuze 30,5 cm Spgr. L/3,6 Bdz u. Kz (m.Hb)
  • ^A Note on Sources: "Service Major Caliber Projectiles of the German Navy: Technical Report No. 395-45" lists a 30.5 cm Psgr. L/4,9 (m.Hb) projectile, a 30.5 cm Spgr. L/5 Bdz. (m.Hb) projectile and a 30.5 cm Spgr. L/4,8 Kz. (m.Hb) projectile, all of 915 lbs. (415 kg), and states that these are for the 30.5 cm SK L/50 guns. This is apparently the source used for "Naval Weapons of World War Two" which lists projectiles of this weight for both the 30.5 cm SK L/50 guns and the prototype 30.5 cm SK C/39 gun. However, these projectiles are not listed in M.Dv. Nr. 170,54 which was issued in 1940 nor in M.Dv. Nr. 234,6 which was issued in 1941. While these projectiles may not have existed, it is possible that they may have been developed sometime after 1941. Another alternative is that they may have been developed and used only for the prototype 30.5 cm SK C/39 gun. This alternative seems reasonable, and so I list these projectiles only for this gun.
  • ^German HE Base and Nose Fuzed projectiles with ballistic caps had a rod between the nose of the shell and the fuze to improve performance when striking obliquely. See details on 12.7 cm SK C/34 datapage.

Range

Range with 915 lbs. (415 kg) APC for coastal artillery
Elevation Distance
49.0 degrees about 46,800 yards (42,800 m)

The APC L/4,9 shell had a significantly better ballistic shape than the previous projectiles. It is noted as being "of longer range" than the older APC, which I take to mean that the newer projectile would have had a longer range when fired at the same elevation.

Range with 551 lbs. (250 kg) Coastal HE L/3,6 Shell for coastal artillery
Elevation Distance
49.1 degrees (?) 56,200 yards (51,400 m)

Mount/Turret Data

Designation N/A
Weight N/A
Elevation N/A
Elevation Rate N/A
Train N/A
Train Rate N/A
Gun recoil N/A
Loading Angle N/A

Sources

"Naval Weapons of World War Two" by John Campbell
"German Artillery of World War Two" by Ian Hogg
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"Service Major Caliber Projectiles of the German Navy: Technical Report No. 395-45" by U.S. Naval Technical Mission to Europe

Page History

24 April 2008 - Benchmark
19 May 2012 - Updated to latest template
07 March 2020 - Converted to HTML 5 format
31 December 2022 - Added Note on Sources regarding the 30.5 cm Psgr. L/4,9