Abstract: An obturating band of the despun variety is manufactured within the channel of a projectile assembly. A split ring polymer pre-band is clamped around the band seat of the projectile assembly and the free ends are welded together to form a continuous ring around the diameter of the projectile assembly within the encircling channel. One free end includes a male connector and the other free end includes an undersized female receptacle. Upon exposure to ultrasonic energy, the free ends are welded together at a scarf joint. A calculated amount of extra material which is present in the male connector is allows the joint to weld itself. The joining surfaces are positioned on indented sections of the free ends such that the resulting obturating band does not bulge at the joint. The obturating band is constructed to slip against the band seat and, therefore, is allowed to rotate at a rate independent of the underlying projectile.

Abstract: A method of forming a gas seal without molds is provided by the use of a chemically modified silicon rubber that is rapidly polymerized upon exposure to ultraviolet radiation. The aft end of the sabot is coated with the rubber compound using spraying or flow coating technologies. The coating layer is deposited to a desired thickness. Then the coating layer is exposed to ultraviolet radiation which causes the polymerization of the silicone rubber compound. A hard, cured gas seal is produced by the polymerization reaction.