As to checking barrel convergence in screw chokes guns, you might suggest the writer check all his chokes. From time to time, choke makers don’t quite keep their tolerances tight enough and individual chokes pattern off center. Switching the chokes from top to bottom and repatterning will rule this out. Just a thought, always eliminate the cheap stuff first.
Very good advice to check the chokes first. I haven’t seen any which were too far out, but it sure could happen. Most of the barrel threading processes used are based on alignment with the bore. If the bore’s right, then the barrel threads are right. Not so always with chokes. Since the chokes are often made by third parties and are not mated to the gun in which they will be used, anything can happen. Some readers have written in with concentricity tests they have run on aftermarket chokes. There was nothing flagrant, but things weren’t perfect either.
Of course, no good Junior Technoid worth his salt ever checks the simple stuff first. You check the hard, complicated stuff first so that you can waste the maximum amount of time on yet another fruitless project. Life is too easy as it is. It’s just not fair to make it any easier by doing something sensible.
The Technoid writing for Shotgun Report, LLC
(Often in error, never in doubt.)