Designed to arm commerce-raiding heavy cruisers and for coastal defense, a single prototype was built but this weapon did not enter service use. There is a Bundesarchive document for this weapon, RH 8/3089K, but it is not yet digitized and available on the internet as of this time (2024).
Actual barrel length was 55.74 calibers. Actual bore diameter was 30.50 cm (12.008").
| 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 |
| 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: about 52.7 lbs. (23.9 kg) TNT 4 HE L/4,8 nose fuze: about 81.6 lbs. (37.0 kg) TNT 4 Coastal HE L/3,6 base and nose fuze: 30.09 lbs. (13.650 kg) TNT 5 |
| 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) 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: As discussed on the 30,5 cm SK L/50 datapage, there is conflicting information regarding which 30,5 cm shells were used for that gun and which ones were used for the 30,5 cm SK L/56 gun. The conclusion reached was that the 405 kg (892.8 lbs.) projectiles were used for the older gun while the newer prototype gun used the 415 kg (915 lbs.) projectiles. See the 30,5 cm SK L/50 ammunition notes for more information.
- ^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 the 12.7 cm SK C/34 datapage.
- ^The Coastal HE L/3,6 base and nose fuze burster was made entirely with FP 1. Burster weight (reiner Sprengstoff) from M.Dv. Nr. 170,54.
| 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.
| Elevation | Distance |
|---|---|
| 49.1 degrees (?) | 56,200 yards (51,400 m) |
| 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 |
"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. 393-45" by U.S. Naval Technical Mission to Europe
"Übersicht über die für die Marinegeschütze und deren Abk K zu verwendende Munition und ihre Einzelteile einschließlich Salut-
und Manöverladungen" M.Dv. Nr. 198 by Oberkommando der Kriegsmarine
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
20 January 2024 - Corrected typographical error on source document reference
25 August 2024 - Added burster note, Source Note and comment on Bundesarchiv document
21 December 2024 - Added Bundesarchive sketches