A bullet may have its base shaped such that explosive from the cartridge or chamber causes the bullet to spin. A bullet may have any shape to the base that causes spinning that closely or exactly matches the rifling of a particular rifle. The base may be structured to achieve an impellor or turbine action to angularly accelerate the bullet while the bullet is being acted upon by an axial force from a propellant explosion during free travel within the gun or while travelling along the rifling.