The 7.5-cm Pak 41 was the largest of the German taper-bore guns, but was prevented by the general tungsten shortage then prevalent in Germany from becoming the standard German army heavy antitank gun.

The German taper-bore guns were an odd off-shoot from the main avenue of anti-tank development that, although successful, foundered for the simple fact that the German war economy could not afford the raw materials required to produce them. Three guns were produced and issued for service, and all relied on what is commonly known as the Gerlich principle. In simple terms this involved the use of a small projectile core made from tungsten, a hard and very dense metal ideal for punching a way through armour plating. In order to provide this tungsten core with the maximum punch the Gerlich system involved the use of guns with calibres that tapered downwards in size from the breech to the muzzle. The special projectiles involved used flanged or ‘skirted’ forms that allowed the flanges to fold back as the bore narrowed. This had the advantage of increasing the emergent velocity of the projectile, enabling it to travel farther and to hit the target harder. The principle was attractive to the German ordnance designers who adapted it for the anti-tank gun, but the principle had some disadvantages: to ensure the maximum power of the gun expensive and relatively rare tungsten had to be used for the projectile core, and the guns themselves were costly to produce.

The first of the taper-bore guns to enter service was the 2.8-cm schwere Panzerbüchse 41 (2.8-cm sPzB 41), which was really little more than a heavy anti-tank rifle, with a bore that tapered from 28mm (1.1 in) at the breech to 20 mm (0.787 in) at the muzzle. It used a light carriage, but an even lighter version of the carriage was produced for the German airborne formations. Both types were still in use at the end of the war.

Second of the taper-bore guns was the 4.2-cm leichte Panzerabwehrkanone 41 (4.2-cm lePak 41, or light anti-tank gun 41). This used the carnage of the 3.7-cm Pak 35/36 but the ordnance was tapered from 40.3 mm (1.586mm) at the start to 29.4mm (1.157 in) at the muzzle. These guns were issued to German airborne units.

Largest of the trio was the 7.5-cm Pak 41. This was a very powerful and advanced gun in which the bore decreased from 75 mm (2,95 in) to 55 mm (2.16 in). At one time this gun showed so much promise that it almost took over from the 7.5-cm Pak 40 as the standard German anti-tank gun, but despite having a better armour piercing performance it was passed over because of the German tungsten shortage. Tungsten was normally used for the machine tools to produce more weapons, but the raw materials had to be brought into Germany by blockade runners and when these were repeatedly intercepted on the high seas the supplies dwindled. It was a choice between anti-tank guns and machine tools, and the result had to be the machine tools. Thus production of the taper-bore guns ceased. Only 150 Pak 41s were made, and once their ammunition had been expended they passed from use. The same applied to the other two guns, though the sPzB 41 was still in use in 1945 as its small projectiles made few demands on available stocks.

Specification

2.8-cm sPzB 41

Starting calibre: 28 mm ( 1.1 in)

Emergent calibre: 20 mm (0.787 in)

Length of barrel: 1.7 m (5 ft 7 in)

Weight: in action 223 kg (492 lb)

Traverse: 90°

Elevation:-5° to+45°

Muzzle velocity: AP 1400 m (4,593 ft) per second

Projectile weight: AP 0.124 kg (0.27 lb)

Armour penetration: 56 mm (2.205 in) at 365 m (400 yards)

4.2-cm lePak 41

Starting calibre: 40.3 mm (1.586 in)

Emergent calibre: 29.4 mm (1.157 in)

Length of barrel: 2,25 m (7 ft 4.6 in)

Weight: in action 560 kg (1,234.5 lb)

Traverse: 60°

Elevation:-8° to+25°

Muzzle velocity: 1265 m (4,150 ft) per second

Projectile weight: AP 0.336 kg (0.74 lb)

Armour penetration: 72 mm (2.835 in) at 455 m (500 yards)

7.5-cm Pak 41

Starting calibre: 75 mm (2.95 in)

Emergent calibre: 55 mm (2.16 in)

Length of barrel: 4.32 m (14 ft 2 in)

Weight: in action 1390 kg (3,064 lb)

Traverse: 60°

Elevation:-10° to+ 18°

Muzzle velocity: AP 1230 m (4,035 ft) per second

Projectile weight: AP 2.5 kg (5.51 lb)

Armour penetration: 171 mm (6.73 in) at 455 m (500 yards)