Squeeze bore guns saw only limited use in World War II.
Manufacturing such weapons was impossible without advanced technologies and high production standards.
Besides Germany, the only country to bring such weapons to mass production was Britain, with the Littlejohn adaptor which, although not a gun in itself, used the same principle.
An attempt by a Soviet design bureau headed by V. G. Grabin in 1940, failed because of technological problems.
In the US, reports about the sPzB 41 inspired a series of experiments with 28/20 barrels and taper bore adaptors for the 37 mm Gun M3; the work started in September 1941 and continued throughout the war, with no practical success.

The sPzB 41 combined good anti-armor performance at short range (for example, at least once a shot penetrated the lower front plate of the heavy IS-1) and a high rate of fire with small, lightweight (for anti-tank gun), dismantleable construction.

However, it also had several shortcomings, such as:
The barrel was hard to manufacture and had a short service life (about 500 rounds)
It had a very weak fragmentation shell
Its use of tungsten for armor-piercing shells
Its short effective range
Its relatively weak beyond-armour effect
Some authors that criticize the sPzB 41 concentrate mainly on the short service life of its barrel.
However, its chance of survival after 500 short-range shots was slim anyway.
High-velocity guns with "normal" barrel construction also had a short service life, e.g. for the Soviet 57-mm ZiS-2 it was about 1,000 shots.
In the end, the factor that brought production of the sPzB 41 to a halt was the shortage of tungsten.
Squeeze bore guns saw only limited use in World War II. Manufacturing such weapons was impossible without advanced technologies and high production standards. Besides Germany, the only country to bring such weapons to mass production was Britain, with the Littlejohn adaptor which, although not a gun in itself, used the same principle. An attempt by a Soviet design bureau headed by V. G. Grabin in 1940, failed because of technological problems. In the US, reports about the sPzB 41 inspired a series of experiments with 28/20 barrels and taper bore adaptors for the 37 mm Gun M3; the work started in September 1941 and continued throughout the war, with no practical success.
The sPzB 41 combined good anti-armor performance at short range (for example, at least once a shot penetrated the lower front plate of the heavy IS-1) and a high rate of fire with small, lightweight (for anti-tank gun), dismantleable construction.
However, it also had several shortcomings, such as:
The barrel was hard to manufacture and had a short service life (about 500 rounds)
It had a very weak fragmentation shell
Its use of tungsten for armor-piercing shells
Its short effective range
Its relatively weak beyond-armour effect
Some authors that criticize the sPzB 41 concentrate mainly on the short service life of its barrel. However, its chance of survival after 500 short-range shots was slim anyway. High-velocity guns with "normal" barrel construction also had a short service life, e.g. for the Soviet 57-mm ZiS-2 it was about 1,000 shots. In the end, the factor that brought production of the sPzB 41 to a halt was the shortage of tungsten.
2.8 cm sPzB 41