7.5 cm KwK 42 explained

7,5 cm KwK 42 (L/70) 7,5 cm Pak 42
Origin:	Germany
Type:	tank gun
Is Ranged:	YES
Is Artillery:	YES
Is Uk:	yes
Wars:	World War II
Manufacturer:	Rheinmetall-Borsig AG
Unit Cost:	12,000 Reichsmark
Production Date:	1942-45
Part Length:	bore (70 calibres)
Cartridge:	Fixed QF 75 × 640mm R
Cartridge Weight:	armour-piercing (APCBC-HE) Pzgr 39/42
Rate:	6 rounds per minute
Elevation:	-8° to +20°

The 7.5 cm KwK 42 L/70 (from 7.5 cm Kampfwagenkanone 42 L/70) was a 7.5 cm calibre German tank gun used on German armoured fighting vehicles in the Second World War. The gun was the armament of the Panther medium tank and two variants of the Jagdpanzer IV self-propelled anti-tank gun. On the latter it was designated as the "7.5 cm Panzerabwehrkanone 42" (7.5 cm Pak 42) anti-tank gun.

Design

The increased muzzle velocity and operating pressure of the new gun required a new armour-piercing projectile to be designed. The PzGr. 39/42 was the result, and apart from the addition of wider driving bands it was otherwise identical to the older 7.5 cm PzGr. 39. The wider driving bands added a little extra weight, from 6.8 kg for the old PzGr.39, to 7.2 kg for the new PzGr.39/42.^[1]

The gun was fired electrically, the primer being initiated using an electric current rather than a firing pin. The breech operated semi-automatically so that after the gun had fired, the empty shell casing was automatically ejected, and the falling wedge type breech block remained down so that the next round could be loaded. Once the round was loaded the breech closed automatically and the weapon was ready to be fired again. Three different types of ammunition were used: APCBC-HE, APCR and HE.

Data for KwK 42 and Pak 42

Type: Tank gun (KwK 42), Anti-tank gun (Pak 42)
Caliber: 7.52NaN2
Shell: 75×640 mm R
Barrel length in calibres

Barrel length: 5.25m (17.22feet)
Breech: semiautomatic, falling wedge
Weight with muzzle brake and breech: 1000kg (2,000lb)
Recoil length: 400 mm (normal), 430 mm (maximum)
Maximum range: 10km (10miles) indirect
Sight: TZF 12 or 12a (Panther), Sfl.ZF 1a (Jagdpanzer IV/70 (A) and (V))

Ammunition

Panzergranate 39/42 (Pzgr. 39/42)

Type: Armour Piercing Capped Ballistic Cap, High Explosive
Projectile weight: 6.8kg (15lb)
Explosive filler: 18 g of phlegmatized RDX
Round weight: 14.3kg (31.5lb)
Round length: 893.2mm
Cartridge case length: 640mm
Muzzle velocity: 935m/s

Penetration of an armoured plate 30 degrees from vertical
Range	100 m	500 m	1000 m	1500 m	2000 m
Penetration (mm)	138	124	112	99	89

Panzergranate 40 (Hk) (Pzgr. 40/42)

Type: Armour Piercing, Composite Rigid
Projectile weight: 4.75kg (10.47lb)
Round weight: 11.55kg (25.46lb)
Round length: 875.2mm
Cartridge case length: 640mm
Muzzle velocity: 1130m/s

Penetration of an armoured plate 30 degrees from vertical
Range	100 m	500 m	1000 m	1500 m	2000 m
Penetration (mm)	194	174	149	127	106

Sprenggranate 42 (Sprgr. 42)

Type: High explosive
Projectile weight: 5.74kg (12.65lb)
Explosive weight: 0.650 kg (1.66 lb) (2,720 Kilojoules)
Round weight: 11.14kg (24.56lb)
Round length: 929.2mm
Cartridge case length: 640mm
Muzzle velocity: 700m/s

Penetration comparison

Ammunition type
Muzzle velocity (m/s)	100 m	250 m	500 m	750 m	1000 m	1250 m	1500 m	2000 m	2500 m	3000 m
Muzzle velocity (m/s)	Penetration (mm)
Pzgr. 39/42 (APCBC)	935m/s	185	179	168	158	149	140	132	116	103	91
Pzgr. 40/42 (APCR)	1130m/s	265	253	234	216	199	184	170	145	124	105

References

Gander, Terry and Chamberlain, Peter. Weapons of the Third Reich: An Encyclopedic Survey of All Small Arms, Artillery and Special Weapons of the German Land Forces 1939-1945. New York: Doubleday, 1979
Hogg, Ian V. German Artillery of World War Two. 2nd corrected edition. Mechanicsville, PA: Stackpole Books, 1997
Penetration data extracted from a French DoD publication "Le Panther" Ministere de la Guerre, Section Technique de l'Armee, Groupement Auto-Chars, 1947.

Notes and References

US Army Technical Manual TM9-1985-3, United States Government Printing Office Washington, 1953