Gun

A gun for use alternately with a shotgun shell and a bullet, comprising:

• a. a barrel having spiraled rifling, an axial bore, and a muzzle at an end of the barrel,
• b. a first tubular integral element attachable to the muzzle of the barrel and having a first end and a second end, the inner surface of the element being formed with longitudinally-extending vanes to remove spiral motion from shot to prevent it from spreading as it leaves the gun, the inner surface of the tubular element consisting of a cylindrical bore extending entirely therethrough and coaxial with the bore of the barrel, the tubular element consisting of a first portion located adjacent the first end of the element adjacent the muzzle and having no vanes, and a second portion located adjacent the second end of the element having vanes which extend inwardly a substantial distance, thereby defining a cylinder coaxial with and having a smaller diameter than the bore of the barrel, and a third portion between the other two portions having parts of the vanes which increase smoothly in a radial extent from a zero radial extent at the first portion to the full radial extent at the second portion while the bore remains the same size, the second and third portions extending substantially the same substantial axial distance, and
• c. a second tubular element provided with gas vents interposed between the muzzle of the barrel and the first-mentioned first tubular element, the outer end of the second tubular element being provided with internal threads and the first tubular element being provided at the said first end with cooperating external threads, the first tubular element being provided with flat wrench-engaging surfaces.