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. Unlike German guns of this caliber, there was no "fore charge" used in these weapons, all the propellant charge was in a single 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 use 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).
|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|
|Rate Of Fire||3 rounds in first minute with ready ammunition, 1 to 2 rounds per minute afterwards|
|Projectile Types and Weights||Austria-Hungary 1
AP L/3,1 2crh: 992 lbs. (450 kg)
APC L/3,7 4.5crh: about 996 lbs. (452 kg)
APC L/4,3 5crh: about 1001 lbs. (454 kg)
Common L/4,0: 992 lbs. (450 kg)
AP: 8.8 lbs. (4.0 kg) TNT
Common: 58.9 lbs. (26.7 kg) TNT
AP 2crh: 37.3 in (94.8 cm) 3
APC 4.5crh: about 44.7 in (113.6 cm) 4
APC 5crh: about 51.9 in (131.9 cm) 4
Common: about 48.0 in (122 cm)
|Propellant Charge 5||Austria-Hungary
Non-K10: 302.0 lbs. (137 kg) 25/660 mm M97 f.R.P.
K10 pre-war: 308.6 lbs. (140 kg) 25/660 mm M97 f.R.P. 6
K10 about 1913:(142 kg) 7
|Cartridge Case Size and Weight||305 mm x 1,372R 8
153.4 lbs. (69.6 kg)
|Muzzle Velocity for AP||Austria-Hungary
2,625 fps (800 mps)
|Working Pressure||18.4 tons/in2 (2,900 kg/cm2)|
|Approximate Barrel Life||200 rounds|
|Ammunition stowage per gun||Radetzky: 75 - 76 rounds 9
Viribus Unitis: 82 rounds 10
- ^The original AP projectiles for these guns were 2crh and had neither an AP cap nor a ballistic cap. In other words, they were AP, not APC projectiles. About 1912-13 the navy refitted these projectiles with AP caps and windshields, making them about 4.5crh. This overall length was limited by the hoists on the Radetzky class. The hoists on the later Tegetthoff class could accommodate longer shells, and these ships were accordingly given AP caps and 5crh ballistic caps. It is probable that the 4.5crh and 5crh shared the same shell body and AP cap with the only difference being the ballistic cap. See sketches below. Weights given here for the APC 4.5crh and APC 5crh projectiles are my estimates.
- ^The figures for Italian service are an assumption based upon notes in "Naval Weapons of World War Two" by John Campbell.
- ^Length of AP 2crh based upon measurements of an existing projectile at the Museum of Military History, Vienna.
- ^Lengths of APC 4.5crh and APC 5crh projectiles are based upon measurements of incomplete APC 5crh shell bodies located at the Museum of Military History, Budapest and estimates based upon war-time photographs of completed projectiles.
- ^Unlike German guns of this caliber, all of the propellant for these Škoda guns was in a single brass cartridge.
- ^This is an estimate based upon the larger chamber size of the K10.
- ^A new propellant formulation was introduced shortly before the start of the war which was cooler burning and produced less smoke. The weight given here is an estimate.
- ^A sealer/pusher pad extended from the mouth of the cartridge by about 1.8 in (4.6 cm).
- ^Outfit for the Radetzky class was 38 AP and 38 Common per gun. Nine projectiles were stored in the rear of each gunhouse, which also helped to balance the turret. There was actually space in the mounting for about 90 rounds, but they never carried this many. A Note on Sources: Friedman in "Naval Weapons of World War One" says 84 rounds per gun were carried but this seems to have double counted the ready rounds.
- ^Outfit for Tegetthoff class was 38 AP and 38 Common per gun in magazines plus another six rounds per gun (18 total) in the in the rear of each gunhouse, which also helped to balance the turret. There was actually space in the mounting for about 100 rounds, but they never carried this many.
- There are two 30.5 cm projectiles on display in the yard of the Museum of Military History, Budapest. These are incomplete 5crh types which lack AP caps and windshields, consisting of only the cast steel body. There is also a 2crh projectile at the Museum of Military History, Vienna.
|Elevation||992 lbs. (450 kg) AP 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)|
|Range||992 lbs. (450 kg) AP 2crh Shell||996 lbs. (452 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)||---|
Data is from "Naval Weapons of World War One."
|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 - see sketch below. 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.
- Many sources state that under battle conditions that the gun houses could not be ventilated as they would have sucked in the propellant gasses and be uninhabitable after no more than 15 minutes once the ventilation was shut down. Recent research by Mihály Krámli throws doubt on this scenario and states that the oxygen supply was probably adequate.
- Projectiles were stored nose-down hanging by chains from the shell room overhead.
"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: 1904-1914] and "A Használhatatlan Lövegtornony Mítosza: Legenda Vagy Valóság?" [The Myth of the Useless Turret: Legend or Reality?]
Special help from Daniel Papp and András Hatala
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
07 April 2020 - Added ammunition data per research by Mihály Krámli and sketches by András Hatala
11 May 2020 - Modified note regarding turret oxygen supply, added sketch of gap between gunhouse and barbette