Unless the precise barrel wall thickness is known along the muzzle end of the barrels for about the last 10" or so, it is not advised to consider "jug choking."
This process involves the removal of metal from the barrel wall to create an enlarged "chamber " area just short of the muzzle. The shot charge expands into this "jug" and is then constricted again toward the muzzle end of the jug, effectively creating choke. How much choke depends on the diameter differential between the inside of the relieved jug portion and the remaining original barrel tube.
Jug choking is NOT a job for the home hobbyist.
In any case, the jug section THINS the barrel wall. Albeit in a very low pressure area.
Personally, I dislike jug chokes. And I've found them only marginally effective, and that modern shot cup wads and cylinder choke are all I need to hit with confidence at virtually any reasonable distance.
|