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 75 mm Second World War era vehicle mounted gun, used as the primary armament of the German Panzer IV (F2 models onwards) medium tank and the Sturmgeschütz III and Sturmgeschütz IV assault guns (F models onwards).

The design of the KwK 40 was adapted from the similar towed anti-tank gun, the 7.5 cm Pak 40. It replaced the short-barrel 7.5 cm KwK 37 L/24 close-support gun, providing a huge improvement in firepower for mid-war tank designs. It came in two versions, with L/43 and L/48 barrel lengths, the former used during 1942 and early 1943, and the latter after that point. Along with the Pak 40, the KwK 40/StuK 40 was the most numerous anti-tank gun of the German army.

History

When mounted on a casemate-armored assault gun-designated vehicle (Sturmpanzer) instead of a turreted tank, the weapon was called Sturmkanone 40 (StuK 40). Both the KwK 40 and StuK 40 were developed from the towed 7.5 cm Pak 40 anti-tank gun. The length of the ammunition used was shortened to allow for easier storage of said ammunition in vehicles the KwK 40 and StuK 40 would be mounted on.

The KwK 40 L/43 was mounted on the Panzer IV from April 1942 until June 1943. All 225 vehicles of the Panzer IV F2 mounted the L/43 with a ball shaped muzzle brake. About a 1,000 out of the 1,687 vehicles of the Panzer IV Ausf. G mounted the L/43 with a double baffle muzzle brake. The StuG III with the L/43 gun was designated as Ausf. F. of which only 120 were equipped with the L/43 (the remaining 246 having the longer KwK 40 L/48 version). All StuG III production runs through Ausf. F/8 to G mounted the longer L/48. The 780 original Jagdpanzer IV tank destroyers mounted the Pak 39 variant of the L/48 gun, the later Panzer IV/70 mounted the StuK 42 L/70.

The L/48 was 334 mm (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 one-piece ammunition was used.

As with the 7.5 cm 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 [1]

Penetration comparison

Penetration in mm, armor plate inclined at 30 degrees from vertical[2]
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 KwK 37 L/24 1766.5 mm K.Gr.Patr.rot.Pz 385 m/s (1,260 ft/s) 41 39 35 33 30
7.5 cm StuK 40 L/43 3281   mm Pzgr.Ptr.39 740 m/s (2,400 ft/s) 99 91 82 72 63
7.5 cm KwK 40 L/48 3615   mm Pzgr.Ptr.39 790 m/s (2,600 ft/s) 110 97 86 75 64
7.5 cm KwK 40 L/48 3615   mm Pzgr.Ptr.40 990 m/s (3,200 ft/s) 143 120 97 77
Penetration figures (90 degrees) uses American and British 50% success criteria,
and allowing direct comparison to foreign gun performance.[3]
Gun typeAmmunition typeMuzzle velocity
(m/s)		Penetration (mm)
100 m 250 m 500 m 750 m 1000 m 1250 m 1500 m 2000 m 2500 m 3000 m
7.5 cm StuK 40 L/43 APCBC 740 m/s (2,400 ft/s) 133 128 121 114 107 101 95 85 75 67
7.5 cm StuK 40 L/43 APCR 920 m/s (3,000 ft/s) 173 164 151 139 127 117 108 91 77 65
7.5 cm KwK 40 L/48 APCBC 750 m/s (2,500 ft/s) 135 130 123 116 109 103 97 86 76 68
7.5 cm KwK 40 L/48 APCR 930 m/s (3,100 ft/s) 176 167 154 141 130 119 109 92 78 66

Usage of KwK or Pak/StuK variant

L/43

L/48

See also

Weapons of comparable role, performance and era

References

  1. ↑ http://www.quarryhs.co.uk/ammotable8.html
  2. ↑ Sturmgeschutz & Its Variants, Walter J. Spielberger, P67, ISBN 0-88740-398-0
  3. ↑ Bird, Lorrin Rexford; Livingston, Robert D. (2001). WWII Ballistics: Armor and Gunnery. Overmatch Press. p. 61.
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