It is not the difference in the bore at 15" from the muzzle and the muzzle. It is the difference between the bore at 3" (or 2" or 4")from the muzzle and the muzzle. That is why I brought up the English gun Dig identified as the Vena Contracta. If you measured the constriction in the last 15" of the bore of a Vena Contracta it would be about 55/1000ths or improved full yet it shot a cylinder pattern. If you measured the constriction in the last 27" of the bore (30" barrel)it would be 99/1000ths or full full full choke. Yet the Vena Contracta gave cylinder patterns.

Last edited by AmarilloMike; 03/25/14 08:52 PM.

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