7.5 cm KwK 42

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.

7,5 cm KwK 42 (L/70) 7,5 cm Pak 42
The 7.5 cm KwK 42 L/70 on a Panther Ausf. A tank
Type	tank gun
Place of origin	Germany
Service history
Used by	Nazi Germany
Wars	World War II
Production history
Designer	Rheinmetall-Borsig AG
Manufacturer	Rheinmetall-Borsig AG
Unit cost	12,000 Reichsmark
Produced	1942-45
Specifications
Mass	1,000 kg (2,204.6 lb)
Barrel length	525 cm (17 ft 3 in) bore (70 calibres)
Shell	Fixed QF 75 × 640mm R
Shell weight	7.2 kg (16 lb) armour-piercing (APCBC-HE) Pzgr 39/42
Calibre	75 mm (2.95 in)
Elevation	-8° to +20°
Rate of fire	6 rounds per minute
Muzzle velocity	935 m/s (3,070 ft/s)
Maximum firing range	9,850 m (32,316 ft)

Despite its shell being the same diameter of the low velocity M4 Sherman tank armament 75mm gun M3,the Panthers 7.5 cm KwK 42 was considered one of the deadliest and most accurate guns mounted on an armored vehicle in the early part of WW2 due to his added gunpowder and longer casing, causing the tank round to achieve very high penetration at larger velocities at approximately 3,300 f/s. The shell could penetrate through the front of an M4 Sherman and go out the back of the tank. The Panthers gun was so powerful it even had better penetration than the Tiger I 8.8 cm KWK 36 gun due to its higher velocities.

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: 7.5 cm (2.95 in)
• Shell: 75×640 mm R
• Barrel length in calibres: 70
• Barrel length: 5.250 m (17 ft 2.7 in)
• Breech: semiautomatic, falling wedge
• Weight with muzzle brake and breech: 1,000 kg (2,200 lb)
• Recoil length: 400 mm (normal), 430 mm (maximum)
• Maximum range: 10 km (6.2 mi) 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: 6.8 kg (15 lb)
• Explosive filler: 18 g of phlegmatized RDX
• Round weight: 14.3 kg (32 lb)
• Round length: 893.2 mm (2 ft 11.17 in)
• Cartridge case length: 640 mm (2 ft 1 in)
• Muzzle velocity: 935 m/s (3,070 ft/s)

Penetration of an armoured plate 30 degrees from vertical^[2]

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: 4.75 kg (10.5 lb)
• Round weight: 11.55 kg (25.5 lb)
• Round length: 875.2 mm (2 ft 10.46 in)
• Cartridge case length: 640 mm (2 ft 1 in)
• Muzzle velocity: 1,130 m/s (3,700 ft/s)

Penetration of an armoured plate 30 degrees from vertical^[2]

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: 5.74 kg (12.7 lb)
• Explosive weight: 0.650 kg (1.66 lb) (2,720 Kilojoules)
• Round weight: 11.14 kg (24.6 lb)
• Round length: 929.2 mm (3 ft 0.58 in)
• Cartridge case length: 640 mm (2 ft 1 in)
• Muzzle velocity: 700 m/s (2,300 ft/s)

Penetration comparison

Calculated penetration (90 degrees) uses American and British 50% success criteria,
and allowing direct comparison to foreign gun performance.^[3]

Ammunition type	Muzzle 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
Pzgr. 39/42 (APCBC)	935 m/s (3,070 ft/s)	185	179	168	158	149	140	132	116	103	91
Pzgr. 40/42 (APCR)	1,130 m/s (3,700 ft/s)	265	253	234	216	199	184	170	145	124	105

See also

Weapons of comparable role, performance and era

• British Ordnance QF 17 pounder
• US 76 mm gun M1
• USSR D-10 tank gun
• Japan Type 5 75 mm tank gun