These were Bofors guns used to arm small torpedo boats and minelayers. Four of the torpedo boats were captured by the Germans during World War II who converted them into torpedo recovery boats. By January 1941 the 10 cm guns had been removed and replaced by a single 10.5 cm/45 (4.1") Tbts L/45 gun. It is not known what happened to the removed 10 cm guns, they may have ended up in coastal defense batteries. All four of the captured boats survived the war and were returned to Norway.
A Note on Sources: "Naval Weapons of World War Two" describes these as 101.6 mm/40 (4.0") QF Bofors, but all German records note them as 10 cm (3.9").
| Designation | Norway: 10 cm/40 (4.1") Bofors
Germany: 10 cm SK/L 40(N) |
|---|---|
| Ship Class Used On | Norway: Sleipner and Fröya classes
Germany: Löwe class (ex-Sleipner class) |
| Date Of Design | about 1934 |
| Date In Service | 1936 |
| Gun Weight | N/A |
| Gun Length oa | N/A |
| Bore Length | about 157.5 in (4.00 m) |
| Rifling Length | N/A |
| Grooves | N/A |
| Lands | N/A |
| Twist | N/A |
| Chamber Volume | N/A |
| Rate Of Fire | About 12-15 rounds per minute |
| Type | Fixed |
|---|---|
| Projectile Types and Weights 1 | HE L/4,6 (N): 43.0 lbs. (19.5 kg)
HE L/3,7 (N): 43.0 lbs. (19.5 kg) HE L/3,6 base fuze (N): 43.0 lbs. (19.5 kg) Illum L/3,5 (N): 28.2 lbs. (12.8 kg) |
| Complete Round Weight | N/A |
| Bursting Charge | HE: about 2.71 lbs. (1.23 kg) |
| Projectile Length | N/A |
| Cartridge Case Type, Size and Empty Weight | N/A |
| Propellant Charge | HE 2.71 lbs. (1.23 kg) Ngl Rg P (1,5 x 11.8)
Illum: N/A |
| Muzzle Velocity | HE: 2,540 fps (775 mps)
Illum: 1,640 fps (500 mps) |
| Working Pressure | N/A |
| Approximate Barrel Life | N/A |
| Ammunition stowage per gun | N/A |
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Actual German designations HE L/4,6 (N) 10 cm Spgr Patr L/4,6 (N) HE L/3,7 (N) 10 cm Spgr Patr L/3,7 (N) HE L/3,6 base fuze (N) (N) 10 cm Spgr Patr L/3,6 Bdz (N) Illum L/3,5 (N) 10 cm Lg Patr L/3,5 (N)
N/A
| Designation | Single Mounts
Norway: Sleipner (3) and Fröya (4): N/A Germany: Löwe (2): 10 cm MPL (N) |
|---|---|
| Weight | N/A |
| Elevation | about -5 / +30 degrees |
| Elevation Rate | Hand operated, only |
| Train | about -150 / +150 degrees |
| Train Rate | Hand operated, only |
| Gun recoil | N/A |
"Weapons of World War Two" by John Campbell
"German Warships 1815-1945" by Erich Gröner
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"Merkbuch über die Munition für die 10 cm SK/L 40(N) in 10 cm MPL (N)" M.Dv. Nr. 170,68, by Oberkommando der Kriegsmarine, Berlin 1941
"ONI-204: German Naval Vessels" by Navy Department, Office of the Chief of Naval Operations, 13 August 1942
01 July 2025 - New datapage