These were Škoda guns built at the Pilsen works. Fitted to Austria-Hungary's last pre-dreadnoughts and to her only completed dreadnoughts. Used a horizontal wedge breech and the propellant charge was in a brass case.

The Škoda Works of Pilsen produced a total of 65 guns (5 of them were spares) in this caliber. The first 13 were for the Radetzky class and the second 52 were for the Tegetthoff class (also known as the Viribus Unitis class). Only the second series, the guns for the Tegetthoff class, were designated as K10. The K10 differed slightly from the earlier 30.5 cm (12") guns in that its chamber was 1.97 inches (5 cm) longer, which allowed these guns to handle a heavier propellant charge.

Erzherog Franz Ferdinand, Radetzky and Tegetthoff were ceded after World War I to Italy, where they were scrapped and their guns then used as coastal artillery.

Actual bore diameter was 30.50 cm (12.008 inches).

Gun Characteristics

Designation 30.5 cm/45 (12")
30.5 cm/45 (12") K10
Ship Class Used On Austria-Hungary
   30.5 cm/45 (12") - Radetzky class
   30.5 cm/45 (12") K10 - Tegetthoff class

Italy: Coastal Artillery

Date Of Design 1908
Date In Service 1910
Gun Weight 116,070 lbs. (52,650 kg)
119,600 lbs. (54,250 kg) including BM
Gun Length oa 541 in (13.750 m)
Bore Length about 512 in (13.000 m)
Rifling Length 417.6 in (10.606 m)
Grooves (92) 0.115 in deep x 0.271 in (2.92 mm x 6.9 mm)
Lands 0.138 in (3.5 mm)
Twist RH 1 in 25
Chamber Volume N/A
Rate Of Fire 3 rounds in first minute with ready ammunition, 1 to 2 rounds per minute afterwards


Type Separate
Projectile Types and Weights Austria-Hungary 1
   APC L/3,4 2crh: 992 lbs. (450 kg)
   APC L/3,4 4.5crh: 992 lbs. (450 kg)
   APC L/3,4 5crh: 992 lbs. (450 kg)
   Common L/4,0: 992 lbs. (450 kg)

Italy 2
   APC: 997 lbs. (452 kg)

Bursting Charge Austria-Hungary
   APC: 8.8 lbs. (4.0 kg) TNT
   Common: 58.9 lbs. (26.7 kg) TNT


Projectile Length Austria-Hungary
   APC 2crh: about 40.8 in (103.7 cm) 1
   Common: about 48.0 in (122 cm)


Propellant Charge 3 Austria-Hungary
   Non-K10: 302.0 lbs. (137 kg)
   K10: 308.6 lbs. (140 kg) 25/660 mm M97 f.R.P.

   304 lbs. (138 kg)

Cartridge Empty Weight 153.4 lbs. (69.6 kg)
Muzzle Velocity for AP Austria-Hungary
   2,625 fps (800 mps)

   2,510 fps (765 mps)

Working Pressure 18.4 tons/in2 (2,900 kg/cm2)
Approximate Barrel Life 200 rounds
Ammunition stowage per gun Radetzky: 84 rounds 4
Viribus Unitis: 82 rounds 5
  • ^1.11.2The APC projectiles for the Radetzky class were originally 2crh. About 1912-13 the navy refitted these projectiles with longer windshields, making them about 4.5crh. The overall length was limited by the hoists. The hoists on the later Tegetthoff class could accommodate longer shells, and these ships were accordingly given 5crh ballistic caps. I lack the actual lengths for all of these projectiles.
  • ^The figures for Italian service are an assumption based upon notes in "Naval Weapons of World War Two" by John Campbell.
  • ^Propellant was in a single brass cartridge. A new propellant formulation was introduced shortly before the start of the war which was cooler burning and produced less smoke.
  • ^Outfit for the Radetzky class was 42 APC and 42 Common per gun.
  • ^Outfit for Tegetthoff class was 38 APC and 38 Common per gun in magazines plus another six rounds per gun in the turret.


Ranges with Austria-Hungary shells
Elevation 992 lbs. (450 kg) APC 2crh Shell 992 lbs. (450 kg) APC 5crh Shell
3.3 degrees --- 6,560 yards (6,000 m)
6.0 degrees --- 10,930 yards (10,000 m)
16.0 degrees 17,830 yards (16,300 m) 20,890 yards (19,100 m)
20 degrees 19,900 yards (18,200 m) about 24,000 yards (22,000 m)

Armor Penetration

Range 992 lbs. (450 kg) APC 2crh Shell 992 lbs. (450 kg) APC 5crh Shell
KC Side Armor Deck Armor KC Side Armor Deck Armor
6,560 yards (6,000 m) 5.3 in (136 mm) --- 18.7 in (475 mm) ---
19,900 yards (18,200 m) 4.2 in (106 mm) --- --- ---
20,890 yards (19,100 m) --- --- 6.8 in (173 mm) ---

Mount/Turret Data

Designation Two-gun Turrets
   Radetzky (2)

Three-gun Turrets
   Tegetthoff (4) 1a

Weight 2a 3a Two-gun Turrets: 432 tons (439 mt)
Three-gun Turrets: 669-679 tons (680-690 mt)
Elevation 4a Radetzky: -4 / +20 degrees
Tegetthoff: -4 / +20 degrees
Elevation Rate 2.5 degrees per second
Train +140 / -140 degrees
Train Rate 3 degrees per second
Gun recoil 33.5 inches (85 cm)
Loading Angle +2 degrees
  • ^On the Tegetthoff class the heavy weight of the superimposed turrets caused hull distortions, requiring stiffening of the longitudinal frames.
  • ^The superimposed triple turrets were heavier than the lower turrets. Weights of individual turrets all differed slightly. For example, Turret III on Prinz Eugen was 687 tons.
  • ^Some references quote triple turret weights of 616-619 tons (626-629 mt). These are taken from the Škoda plans of October 1909 that used 25 cm turret armor. The actual turrets had 28 cm armor and were consequently much heavier.
  • ^The Radetzky class and Viribus Unitis could elevate all guns to 20 degrees either individually or when coupled together. The other ships in the Tegetthoff class were able to elevate all guns individually to -4 / +20 degrees, but when the guns were coupled together, the elevation range for the center gun was -3 / +15.5 degrees and the outer guns were limited to -4 / +16 degrees.
  • These turrets were poorly protected with thin armor. There was an unprotected slot between the gunhouse and the barbette. The cupolas for the rangefinders on the turret roofs were overly large. A hit on one of these could have peeled back the thin turret roof armor.
  • Under battle conditions the gun houses could not be ventilated as they would have sucked in the propellant gasses. It was estimated that they had no more than 15 minutes of oxygen once the ventilation was shut down.
  • Projectiles were stored nose-down hanging from the shell room overhead.

Additional Pictures


"Naval Weapons of World War Two" by John Campbell
"Naval Weapons of World War One" by Norman Friedman
"The Big Gun: Battleship Main Armament 1860-1945" by Peter Hodges
"The Viribus Unitis Class" article in "Warship Volume II" and "A's and A's" comments in "Warship Volume III" both by Friedrich Prasky
"A Szent István Csatahajó" [The battleship Szent István] by Balogh Tamás and Csepregi Oszkár
"Entwickelung des Schieß - und Artilleriewesens der k. u. k. Kriegsmarine in den letzten Jahren" [Development of the firing and artillery system of the k. u. k. Kriegsmarine in recent years] by kuk Marinetechnische Komitee (ca. 1912)
Original research by Mihály Krámli, author of "Az Osztrák-Magyar Monarchia Cstahajói: 1904-1914" [Battleships of the Austro-Hungarian Empire]
Special help from Daniel Papp

External Sites

Page History

27 November 2007 - Benchmark
18 July 2010 - Updated with information supplied by Mihály Krámli
12 October 2013 - Added pictures of Radetzky turret and cartridge being rammed
01 May 2014 - Added additional gun, ammunition and mounting information, new range and armor penetration tables
20 November 2018 - Converted to HTML 5 format, reorganized notes, added propellant weight for non-K10 guns, added turret weights, added photograph of damaged guns
19 March 2019 - Added photographs of breech from exploded gun and Radetzky
26 March 2020 - Changed 4crh to 5crh per research by Mihály Krámli