7.5 cm KwK 40

7.5 cm KwK 40/L48 on a Panzer IV.

The 7.5 cm KwK 40 (7.5 cm Kampfwagenkanone 40) was a German 7.5 cm Second World War era vehicle mounted gun, used as the primary anti-tank weapon of the German medium tank the SdKfz.161 Panzerkampfwagen IV (Ausf. F2 models onwards) and the SdKfz.142 Sturmgeschütz III (StuG III) assault guns (Ausf. F models onwards). When mounted on an assault gun the weapon was called Sturmkanone 40 (StuK 40). KwK40 and StuK40 was developed from the towed anti-tank gun Pak 40. Ammunition was shortened in length to allow easy storage for KwK40 and StuK40. KwK40 came in both the L/43 and L/48 barrel lengths. Along with the Pak 40, the Kwk 40/StuK 40 was the most numerous anti-tank gun of the German army.

The L/43 version was mounted on the Panzer IV and StuG III for a short period from February 1942 until August 1942. All 225 vehicles of the Panzer IV F2 mounted the L/43 version with a ball shaped muzzle brake. A couple hundred out of 1687 vehicles of the Panzer IV Ausf. G mounted L/43 with a double baffle muzzle brake. The StuG III with the L43 was designated as Ausf. F. Only 120 of the 366 StuG III Ausf.F mounted the L/43 version. The remaining 246 StuG III Ausf. F had the longer L/48 version. All Ausf. F/8 and G of StuG III mounted the longer L/48.

The L/48 was 334mm (13.1 inches) longer and slightly more powerful than the L/43. L/48 became the standard gun from June 1942 until the end of World War II. The gun was fitted with an electric firing mechanism and the breech operated semi-automatically. Only fixed ammunition was used.

• Following number of vehicles mounted L/48 version from June 1942-April 1945
  • Approximately 6000 vehicles of Ausf. G, H, J out of 8800 Panzer IV
  • 7720 vehicles of StuG III Ausf. G + 246 of Ausf.F + 250 vehicles of StuG III Ausf. F/8
  • All 1139 vehicles of StuG IV
  • All 175 vehicles of Marder III Ausf. H + All 975 vehicles of Ausf. M
  • 780 vehicles out of 1998 vehicles of Jagdpanzer IV, the rest mounted 7.5 cm KwK 42.

As with the Pak 40, the muzzle brake of the KwK 40 and Stuk 40 went through a series of design changes. Five types of muzzle brakes were used, gradually increasing the area of exposure to the blast. The designs progressed from tubular type double baffle muzzle brakes to single baffle ball shape muzzle brakes, which proved to be insufficient in reducing recoil, followed by a double flange type from May 1943. The front flange and rear disk type was used from March 1944, followed finally by the double disc type.

Ammunition

Gun maintenance on a Sturmgeschütz III.

KwK 40 used shell 75×495 mm. R

• Pzgr. Patr. 39 KwK 40 (Armour Piercing Capped Ballistic Cap High Explosive round)
  • Muzzle velocity: 790 m/s
  • Projectile: Panzergranate 39 (Pzgr. 39)
  • Projectile weight: 6.80 kg
  • Explosive filler: 18 g of RDX/wax
  • Fuze: BdZ 5103 or BdZ 5103* base fuze
  • Round weight: 11.52 kg
  • Cartridge case height: 495 mm
  • Propelling charge: 2.410 kg of Digl. R.P. G1
  • Primer: electric, model C/22 or C/22 St.

• Pzgr. Patr. 40 KwK 40 (Armour Piercing Composite Rigid)
  • Muzzle velocity: 990 m/s
  • Projectile: Panzergranate 40
  • Projectile weight: 4.10 kg
  • Explosive filler: none
  • Fuze: none
  • Round weight: 8.61 kg
  • Cartridge case height: 495 mm
  • Propelling charge: 2.2 kg of Gu. R.P. 7,7
  • Primer: electric, model C/22 or C/22 St.

• Gr. Patr. 38 HL/B KwK 40 (High Explosive Anti-Tank)
  • Muzzle velocity: 475 m/s
  • Projectile: Gr. 38 HL/B
  • Projectile weight: 4.60 kg
  • Explosive filler: 0.51 kg of RDX/wax
  • Fuze: A.Z. 38 St
  • Round weight: 7.36 kg
  • Cartridge case height: 495 mm
  • Propelling charge: 0.43 kg of Gu. Bl. P.-AO
  • Primer: electric, model C/22 or C/22 St.

• Gr. Patr. 38 HL/C KwK 40 (High Explosive Anti-Tank)

• 7.5 cm Sprgr.Patr.34 KwK 40 (High Explosive) L/48
  • Muzzle velocity: 550 m/s
  • Projectile: Sprgr. 34
  • Projectile weight: 5.75 kg
  • Explosive filler: 0.66 kg of amatol
  • Fuze: kl. A.Z. 23 (0,15) umg. nose fuze
  • Round weight: 8.71 kg
  • Cartridge case height: 495 mm
  • Propelling charge: 0.755 kg of Gu. Bl. P.-AO
  • Primer: electric, model C/22 or C/22 St.

Penetration comparison

(Penetration in mm, armor plate inclined at 30 degrees from vertical)

Gun type	Barrel Length (mm)	Ammunition Type	Muzzle velocity (m/s)	Penetration (mm)
				100 m	500 m	1000 m	1500 m	2000 m
7.5 cm Kan. L/24	1766.5mm	K.Gr.Patr.rot.Pz	385	41	39	35	33	30
7.5 cm StuK 40 L/43	3281mm	Pzgr.Ptr.39	740	99	91	82	72	63
7.5 cm StuK 40 L/48	3615mm	Pzgr.Ptr.39	790	106	96	85	74	64

Vehicles mounted on

L/43

• SdKfz.161/1 Panzerkampfwagen IV Ausf. F2/G (Little to no difference between the two models.)
• SdKfz.142/1 Sturmgeschütz III (StuG III) Ausf. F
• KV-1

L/48

• SdKfz.161/2 Panzerkampfwagen IV Ausf. G (Later production G's.)
• SdKfz.161/2 Panzerkampfwagen IV Ausf. H
• SdKfz.161/2 Panzerkampfwagen IV Ausf. J
• SdKfz.142/1 Sturmgeschütz III (StuG III) Ausf. F/8
• SdKfz.142/1 Sturmgeschütz III (StuG III) Ausf. G
• SdKfz.167 Sturmgeschütz IV (StuG IV)