Patent ID: 7140140
Filing Date: 2006-11-28
Classification: F41A

Abstract:
1. A choke tube having a tube inner shape for defining a design ballistic pattern, comprising: a tube body having a length, a wall, a circumference, an inner surface, an outer circumferential surface, and an end comprising a discharge orifice, the end having a tip, and said body being made of a high-hardness stainless steel; a plurality of slits elongated along the length of the tube and formed through the tube body close to the discharge orifice and spaced at equal intervals around the circumference; and a wear resistant coating applied both on the outer surface of the tube body and on an inner surface of the discharge orifice, wherein the wear resistant coating over the inner surface of the discharge orifice is identical with the wear resistant coating applied on the outer surface of the tube body, wherein the wear resistant coating maintains a particular and bright color corresponding to the tube inner shape even after successive discharges to allow the design ballistic pattern to be identified by the outward appearance of the choke tube, and wherein said coating is selected from the group consisting of a titanium nitride film, a titanium carbide nitride film, a titanium oxide film and a titanium aluminum nitride film.