Abstract: The freebore section of a barrel of a firearm includes a plurality of freebore pads interleaved with a plurality of freebore slots for conveying propellant gases past the bullet upon entry of the bullet into the freebore section to stabilize and maintain the bullet in axial alignment with the axis of the rifled bore of the barrel upon entry of the bullet into the rifled bore.

Abstract: The rifling in a barrel of a firearm is modified in proximity to the muzzle to reduce the radial difference between the land diameter and the groove diameter to urge a bullet to expand fully into the grooves and ensure rotation of the bullet about its longitudinal axis and without any lateral velocity component. Preferably, the land diameter is increased to a diameter somewhat less than the groove diameter but in the alternative the groove diameter may be reduced to a diameter somewhat more than the land diameter.

Abstract: A group of upwardly directed ports disposed in a barrel of a hand held firearm intermediate the chamber and the muzzle of the firearm vent propellant gasses upwardly upon discharge of the firearm to produce a downwardly directed component of thrust to counteract gun rise and muzzle jump. Preferably, the center of the group of ports is in the vicinity of midway between the chamber and the muzzle. The ports may be straight or tapered passages or they may be nozzles.

Abstract: A group of upwardly directed ports disposed in a barrel of a hand held firearm intermediate the chamber and the muzzle of the firearm vent propellant gasses upwardly upon discharge of the firearm to produce a downwardly directed component of thrust to counteract gun rise and muzzle jump. Preferably, the center of the group of ports is in the vicinity of midway between the chamber and the muzzle. The ports may be straight or tapered passages or they may be nozzles.