30.5 cm/50 (12") SK L/50
Updated 17 April 2016
These guns were fitted to many battleships and battlecruisers completed just before and after the start of World War I.  When compared to contemporary British guns in terms of penetrating power, they were superior to the 12"/45 (30.5 cm) and 12"/50 (30.5 cm) guns, and only slightly less powerful than the 13.5" (34.3 cm) guns.  They were, of course, completely outclassed by the 15"/42 (38.1 cm) guns used on the Queen Elizabeth class.

The battlecruisers Derfflinger and Lützow used these weapons at the Battle of Jutland (Skagerrak) to sink the British battlecruisers HMS Queen Mary and HMS Invincible.

The World War I Coastal Defense Battery Kaiser Wilhelm II located near Knocke in Belgium was equipped with four of these guns.

  The mountings for these guns used electric pumps to drive hydraulic elevation gear while the training was all electric.  These guns also had hydraulically worked rammers and breeches, the first fitted to German large-caliber guns.  These changes increased the rate of fire, with most ships having a ROF of 20 seconds while the Kaiser class were reported to have had an overall ammunition supply speed of three rounds in 48 seconds, including all transfers.

In World War II these guns were used only as coastal artillery.  They were then supplied with a more streamlined shell and used a larger propellant charge, giving them increased range.  The best known battery was the six-gun Friedrich August at Wangerooge.  Later, three of these guns on BSG mountings were moved to near Wimille on the Channel Coast.

Constructed from shrunk on tubes and hoops and used the Krupp horizontal sliding wedge breech block.

Actual bore diameter was 30.50 cm (12.008").


Aft turrets of SMS König

Click here for additional Pictures
Gun Characteristics
Designation 30.5 cm/50 (12") SK L/50
Ship Class Used On Helgoland, Kaiser, König and Derfflinger Classes
Date Of Design 1908
Date In Service 1911
Gun Weight
(see Note)
114,309 lbs. (51,850 kg)
Gun Length oa 600.4 in (15.250 m)
Bore Length 569.3 in (14.461 m)
Rifling Length 465.0 in (11.805 m)
Grooves (88) 0.262 in D x 0.118 in W (6.68 mm D x 3.0 mm W)
Lands 0.165 in (4.20 mm)
Twist Increasing RH 1 in 45 to 1 in 30 at the muzzle
Chamber Volume For 551 lbs. (250 kg) shells:  12,052 in3 (197.5 dm3)
For 892.9 lbs. (405 kg) shells:  12,205 in3 (200.0 dm3)
Rate Of Fire 2 - 3 rounds per minute
Note:  The often-seen figure of 171,079 lbs. (77,600 kg) for this weapon actually includes the weight of the Weige (gun cradle).
Type Cartridge - Bag
Projectile Types and Weights
(see Note 7)
World War I
   APC L/3,4 - 894 lbs. (405.5 kg)
   HE L/3,8 - 894.8 lbs. (405.9 kg)

World War II
   APC L/3,4 - 892.9 lbs. (405 kg)
   APC L/4,9 - 915 lbs. (415 kg)
   HE L3,8 base fuze - 915 lbs. (415 kg)
   HE L/5 base fuze - 915 lbs. (415 kg)
   HE L/4,8 nose fuze - 892.9 lbs. (405 kg)

Special Coastal Artillery Projectile
   HE L/3,6 base and nose fuze - 551 lbs. (250 kg)

Bursting Charge World War I
   APC L/3,4 - 25.4 lbs. (11.5 kg)
   HE L/3,8 - 58.2 lbs. (26.4 kg)

World War II
   APC L/3,4 - 25.4 lbs. (11.5 kg)
   APC L/4,9 - N/A
   HE L/3,8 base fuze - 59.5 lbs. (27.0 kg)
   HE L/5 base fuze - N/A
   HE L/4,8 nose fuze - 58.4 lbs. (26.5 kg)
   HE L/3,6 base and nose fuze - 32.0 lbs. (14.5 kg)

Projectile Length World War I
   APC L/3,4 - 40.8 in (103.7 cm)
   HE L/3,8 - 48.38 in (122.9 cm)

World War II
   APC L/3,4 - 40.8 in (103.7 cm)
   APC L/4,9 - 58.8 in (149.5 cm)
   HE L/3,8 base fuze - 45.6 in (115.9 cm)
   HE L/5 base fuze - 60.0 in (152.5 cm)
   HE L/4,8 nose fuze - 52.6 in (133.5 cm)
   HE L/3,6 base and nose fuze - 55.1 in (140 cm)

Propellant Charge World War I
   Main Charge:  201 lbs. (91 kg) RP C/12
   Fore Charge:  76 lbs. (34.5 kg) RP C/12

World War II (as of 1940)
   For APC L/3,4 and HE L/4,8 nose fuze
      Main Charge - 188.3 lbs. (85.4 kg) RP C/32
      Fore Charge - 91.7 lbs. (41.6 kg) RP C/32

   For HE L/3,6 base and nose fuze
      Main Charge - 188.3 lbs. (85.4 kg) RP C/32
      Fore Charge - 135.8 lbs. (61.6 kg) RP C/32

   Total main cartridge weight:  313 lbs. (142 kg)
   Silk bag for fore charge:  5.3 lbs. (2.4 kg)

After 1942 (see Note 3)
   APC L/4,9 - 268 lbs. (121.5 kg) RP C/38 (18/8)
   HE L/3,6  - 315 lbs. (143 kg) RP C/38 (18/8)

Muzzle Velocity
(see Note 6)
World War I
   2,805 fps (855 mps)

World War II
   APC L/3,4 - 2,805 fps (855 mps)
   APC L/4,9 - 2,789 fps (850 mps)
   HE L3,8 base fuze - 2,789 fps (850 mps)
   HE L/5 base fuze - 2,789 fps (850 mps)
   HE L/4,8 nose fuze - 2,805 fps (855 mps)
   HE L/3,6 base and nose fuze - 3,675 fps (1,120 mps)

Working Pressure 20.9 tons/in2 (3,300 kg/cm2)
Approximate Barrel Life 200 rounds
Ammunition stowage per gun
(see Note 4)
Helgoland:  85 rounds
Kaiser:  86 rounds
König and Derfflinger:  90 rounds

1) These guns, like most large caliber German guns of this era, used a "fore charge" which was propellant in a double bag silk case and a "main charge" which was propellant in a brass case.  The brass case helped to seal the breech of the gun.

2) APC shells were painted blue, HE yellow and Training red.  A black painted nose indicated that the shell was armed.

3) I lack the break down between fore and main charges for the 1942 propellant charges.

4) Outfits were typically 70% APC and 30% HE.  Outfit for Derfflinger class was 65 APC and 25 HE per gun.  British post-war documents claim that the König class carried 96 to 100 rounds per gun and that the Kaiser class carried 98 to 103 rounds per gun.

5) "German Battlecruisers of World War One" says that the HE L3,8 weighed 914.9 lbs. (415 kg), all other references quote a weight around 892.9 lbs. (405 kg).  As these projectiles used a base fuze and a thick nose wall, they should be considered more equivalent to SAP rounds.  These rounds could penetrate 6 to 20 feet (2 to 6 m) through unarmored structures before detonating.

6) Using the "Small Battle Load" of just the main charge gave a muzzle velocity of about 2,034 fps (620 mps).

7) Actual Projectile designations were as follows:

World War I
   APC L/3,4 - Psgr. L/3,4 (mhb)
   HE L/3,8 - L/3,8 Bdz

World War II
   APC L/3,4 - Psgr. L/3,4 (mhb)
   APC L/4,9 - Psgr. L/4,9 (mhb)
   HE L/3,8 base fuze - L/3,8 Bdz
   HE L/5 base fuze - L/5 Bdz
   HE L4,8 nose fuze - L/4,8 Kz
   HE L/3,6 base and nose fuze - L/3,6 Bdz u. Kz (mhb)

Diagrams of some of these projectiles and their fuzes and propellant charges may be found at the additional pictures link above.

Range during World War I
Elevation With 894 lbs. (405.5 kg) APC L3,4 Shell
Range @ 13.5 degrees 17,717 yards (16,200 m)
Range @ 16.0 degrees 22,310 yards (20,400 m)
Note:  See elevation note in the "Mounting / Turret" section below.
Range during World War II
Elevation With 892.9 lbs. (405 kg) APC L3,4 Shell
Range @ 45.0 degrees 35,000 yards (32,000 m)
Elevation With 915 lbs. (415 kg) APC L4,9 Shell
Range @ 49.2 degrees 45,166 yards (41,300 m)
Range @ 50.0 degrees 43,200 yards (39,500 m)
Elevation With 551 lbs. (250 kg) HE L3,6 Shell
Range @ 49.1 degrees 56,200 yards (51,400 m)

1) All entries in this table are for coastal artillery batteries.  The range data for the 915 lbs. (415 kg) APC L4,9 shell is from two different sources, which may account for the large difference in range for only a slight change in elevation.

2) The APC L/4,9 shell had a significantly better ballistic shape than the previous ones.  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.

Armor Penetration with 894 lbs. (405.5 kg) APC L3,4 Shell
Side Armor
Deck Armor
14,000 yards (12,800 m)
10.0" (254 mm)
16,000 yards (15,000 m)
9.0" (229 mm)
Note:  Data from "Jutland:  An Analysis of the Fighting."
Armor Penetration with 894 lbs. (405.5 kg) APC L3,4 Shell
Side Armor
Deck Armor
10,940 yards (10,000 m)
13.6" (345 mm)
13,120 yards (12,000 m)
12.0" (305 mm)
Note:  Data from "German Battlecruisers of World War One."
Mount / Turret Data
Designation Two-gun Turrets
   Helgoland class (6):  Drh LC/1908
   Kaiser class (5):  Drh LC/1909
   König class (5):  Drh LC/1911
   Derfflinger class (4):  Drh LC/1912
   Hindenburg (4):  Drh LC/1913

Single Coastal Artillery Turrets
   30.5 cm L/50 Kst.Drh.L.C/37

Weight Ships:  Between 534 to 549 tons (543 to 558 mt)
Coastal Artillery:  271.9 tons (276.26 mt)
(see Note 4)
All ships as built:  -8 / +13.5 degrees
After 1915:  -5.5 to +16.0 degrees

Coastal artillery:   -5 / +50 degrees

Elevation Rate Ships:  4 degrees per second
Coastal Artillery:  10 degrees per second with shell loaded
Train End Turrets:  About +150 / -150 degrees
Beam Turrets:  About +80 / -80 degrees
Coastal Artillery:  -220 / +220 degrees
Train Rate Ships:  3 degrees per second
Coastal Artillery:  4 degrees per second
Gun recoil
(see Note 5)
36.0 in (91.5 cm)
Loading Angle Ships:  about +5 degrees
Coastal Artillery:  0 degrees

1) The mounting weight differences were mainly the result of thicker armor used on the battleships.

2) Run out was by compressed air.  Magazines were below shell rooms on the battleships.  On the Derfflinger class except for Hindenburg, A, B and C turrets had the magazines below the shell rooms, but D turret had the magazine above the shell room for reasons of space.  D turret also did not have the shell hoists broken at the working chamber as did all other 30.5 cm (12") mountings.  Instead, the projectile hoist ran directly from the shell room up to the gunhouse.  Hindenburg had all shell rooms below the magazines as in the battleships.  Hindenburg also differed from her half-sisters by having LC/1913 mountings with half the number of hoists as the the LC/1912, but these hoists ran faster and were still capable of supplying the equivalent of three complete rounds per gun per minute.  The LC/1913 turrets had 7.7 m (25.5 foot) rangefinders on each turret rather than 3 m (10 foot) rangefinders on earlier designs.  The Helgoland, Kaiser and König classes had a machinery level directly below the gunhouse with a handling room below it.  Lower shell and projectile hoists came up to this room and the ammunition was then transferred over to upper hoists which ran up to the gunhouse.  Battlecruisers were similar except for Hindenburg in which the projectile hoists ran directly up to the gunhouse although the propellant hoists were still two-stage.  Training of the gun turrets was electric and gun elevation was hydraulic.  Hydraulic power was provided by two electrically-driven triple pumps.  Rammers were hydraulically powered with fluid being supplied directly from the elevation pump.  Wedge breech mechanisms were hydraulically powered but could be manually operated.  Propellant smoke was removed with two independent suction systems, each with its own motor.  Should one motor fail, the other motor could be coupled to run both systems at a reduced rate.  For at least the Drh LC/1912 turrets, the guns were separated by a 25 mm (1.0") splinter bulkhead.  Following the Dogger Bank action, German mountings were modified to improve flash precautions.  Double flap doors were installed at the beginning and end of the cartridge hoist and ready ammunition was removed from the gun houses.

3) The Kaiser class were the first German battleships to have superfiring turrets.  This allowed them to have one less turret than previous classes (5 vs. 6) yet still be able to fire the same number of guns on the broadside.  The König class had all main guns on the centerline, giving them a heavier broadside than earlier ships.

4) Prinzregent Luitpold was modified just before and the other ships shortly after Jutland (Skagerrak) to increase the maximum elevation from +13.5 to +16.0 degrees.  A few sources claim that the maximum elevation was increased on all ships to 16.5 degrees rather than to 16.0 degrees.  Norman Friedman in "Naval Weapons of World War One" gives conflicting data for maximum elevations and ranges with no explanation.  For that reason, I do not believe this source to be a reliable reference in this matter.

5) The recoil distance given above is the nominal figure.  The absolute, metal-to-metal recoil distance was 38.6 inches (98.0 cm).

6) Derfflinger had a crew of 70 men in C mounting and probably in A and B as well while D mounting had 80 crewmen.

7) The gun axes were (270 cm) apart.

8) Armor thickness given in "Naval Weapons of World War One" by Norman Friedman:

    Face:  11.8 in (30 cm)
    Sides:  9.8 (25 cm)
    Rear:  11.4 in (29 cm) except Kaiser class:  10.6 in (27 cm)
    Roof:  3.1 to 4.3 in (8 to 11 cm) except Helgoland class:  2.8 3.9 in (7 to 10 cm)

    Face:  10.6 in (27 cm)
    Sides:  8.7 in (22 cm)
    Rear:  10.6 in (27 cm)
    Roof:  3.1 to 4.3 in (8 to 11 cm) except Hindenburg:  3.1 to 5.9 in (8 to 15 cm)

Data from
"The Battle of Jutland" by Geoffrey Bennett
"Warship Special 1:  Battle Cruisers," "Jutland:  An Analysis of the Fighting" and "Naval Weapons of World War Two" all by John Campbell
"Battleship Design and Development 1905-1945" and "Naval Weapons of World War One" both by Norman Friedman
"German Warships 1815-1945" by Erich Gröner
"The Big Gun:  Battleship Main Armament 1860-1945" by Peter Hodges
"The German Defenses on the Coast of Belgium" by Lt. Col. H.W. Miller USA in "The Journal of the American Society of Mechanical Engineers" Vol. 42, No. 6, June 1920
"North Sea Battleground:  The War at Sea 1914-18" by Bryan Perrett
"Die Geschichte der deutschen Schiffsartillerie" by Paul Schmalenbach
"German Battlecruisers 1914-18" and "German Battlecruisers of World War One" both by Gary Staff
"German Warships of World War I" by John C. Taylor
"German Capital Ships of World War Two" by M.J. Whitley
M.DV.Nr.170,54 "Merkbuch über die Munition der 30,5 cm SK L/50 der Marine-Küstenartillerie" Berlin 1940, Oberkommando der Kriegsmarine
M.DV.Nr. 234.6 "Vorläufige Beschreibung der 28 cm S.K.L/45, 28 cm S.K.L/50 und 30,5 cm S.K.L/50 in Kst.Drh.L.C.37" Berlin 1941, Oberkommando der Kriegsmarine
Special help from Peter Lienau
Page History

28 December 2008 - Benchmark
26 August 2011 - Added twist and projectile information
31 December 2011 - Added mounting notes and source for picture on Additional Pictures page
24 November 2012 - Added details on mountings
08 December 2014 - Added comment on HE Shell weight, additional armor penetration data, additional information on mountings
29 August 2015 - Additional ammunition and mounting information

17 April 2016 - Corrected typographical error