German 75-mm Antitank Gun—7.5-cm Pak 40, WWII Tactical and Technical Trends, No. 25: May 20, 1943 (Lone Sentry)

Mention of this gun has already been made in Tactical and Technical Trends (No. 18, p. 4). It must not be confused with the 7.5-cm Pak 97/38 which is a German modification of the well-known French 75 (see Tactical and Technical Trends, No. 22, p. 6).

The 7.5-cm Pak 40 is very similar in appearance to the standard German 50-mm antitank gun, the 5-cm Pak 38. However, the following structural differences may be readily noted:

Item 5-cm Pak 38 7.5-cm Pak 40

Shield Curved. Flattened at outer edges Angular. Flat frontal section with two flat side pieces set at an angle of approx. 45° to the plane of the frontal section

Muzzle brake Narrow and elongated Broad and longer

Sighting aperture Rectangular Square

[7.5-cm Pak 40]

[5-cm Pak 38]

The gun proper, i.e., exclusive of the carriage, is essentially the same weapon as the 7.5-cm Kw.K 40*, which is the principal armament of the new German medium tank, the PzKw 4. Two self-propelled versions of the 7.5-cm Kw.K 40 have also been reported, one mounted on the chassis of a PzKw 2, the other on the chassis of the PzKw 38 (t)**. The chief differences between the 75-mm antitank gun and tank gun are probably the substitution of mechanical firing and percussion primer for electric firing and primer; the chamber of the antitank gun is also probably considerably longer. The breechblock is the semi-automatic, horizontally sliding type.

The piece is mounted on a split-trail carriage, with torsion springing; this springing is automatically cut out when the trails are opened. The wheels are of a light alloy and are fitted with solid rubber tires. An interesting feature is a detachable third wheel which can be fitted on near the trail spades, thereby permitting the gun to be man-handled more easily. The shield is of the spaced-armor type like the Pak 38; note also that a protective apron is provided.

Further details on this weapon are as follows:

Over-all length in travelling position 19 ft 2 in

Weight in action 3,350 lbs

Length of barrel 10 ft 6 in

Length of recoil 35.43 in

Elevation 22 degrees

Depression 5 degrees

Traverse 65 degrees

Four types of ammunition are used, namely HE, hollow charge, AP shot, and an armor-piercing tracer shell with a small explosive charge and an armor-piercing cap covered with a ballistic nose. Details on this latter type of ammunition (see sketch at left) are these:

Weight of complete round 27 lbs

Length of complete round 36.14 in

Weight of projectile 15 lbs

Weight of HE filling 3/4 oz

Weight of propellant 6 lb 3/4 oz

Muzzle velocity (estimated) 2,830 f/s

With this AP-HE ammunition it has been estimated that this gun can penetrate homogeneous armor as follows:

Range Normal 30 degrees

500 5.20 in 4.43 in

1,000 4.72 in 4.02 in

1,500 4.27 in 3.62 in

2,000 3.82 in 3.23 in

2,500 3.43 in 2.87 in

The AP shot is the usual German steel casing enclosing a tungsten carbide core; it is fitted with tracer. The muzzle velocity with this ammunition is reported to be 3,250 feet per second.

Comment: Detailed confirmed information on the effectiveness of this weapon is not available as yet. For its size it does have a low silhouette, a desirable feature for an antitank gun. While the muzzle velocity is high, the tube is of monobloc construction and the propellant charge is very large, so that the safety factor is open to question. The Germans have been doubling the length of the chambers in their tank and antitank weapons (e.g., the Russian 76.2-mm gun), and seem to have reached the conclusion that it is worthwhile since they are now producing this 75-mm antitank gun with the long chamber and shell case as a standard weapon.

* Kampfwagon Kanone--used by Germans to designate tank guns.
** A Czech light tank.