Muzzle wear of cannon

Abstract Bore enlargement at the muzzle of cannon can limit their useful lives by causing unacceptable increases in range and azimuth dispersion. This wear is restricted to the lands of the rifling and is mechanical wear resulting from sliding of the projectile. A service projectile travels down the front portion of the tube with the largest yaw possible. This results in centrifugal loading and asymmetric loading caused by propellent gases leaking past the base. With heavy projectiles, high muzzle velocities, etc., the transverse loading sometimes exceeds the load carrying capacity of relatively low-melting, high thermal conductivity rotating bands such as the conventional copper alloy bands. This allows the steel body of the projectile to slide directly on the lands of the rifling and results in increased wear. Basically, the remedy lies in decreasing the transverse loading and/or increasing the load carrying capacity of the rotating bands or the wear resistance of the cannon bore.