This is an
artillery piece in which the
barrel caliber is sharply reduced at some point. A contrast to the
Taper Bore Gun developed at the same time during
World War II, in which the barrel gradually reduces diameter from
breech to
muzzle.
The coned bore achieves the same effect, reducing the diameter of the projectile and thereby enhancing its armor penetrating ability. It also has the added benefit of being much cheaper and easier to produce, as the cone section can be manufactured as a separate unit, and then fitted onto the muzzle, or built directly into the barrel at a later time.
Many military forces have experimented with the concept, but none of these weapons have ever been produced in significant numbers.