Thanks for the replys. The gun is a LC Smith 12 ga about 1949 vintage. The best patterns I have gotten out of the left barrel was with my 12 to 20 ga chambermate using a 20 ga skeet load. Fewer pellets lesson the condition and improve density of the pattern.
A continuous taper seems counterproductive--pellets would be converging at a central point causing deformation. I wonder how they get away with that. My Winchesters all measure with a parallel section, most of them longer than 3/4". I will give Mike a call to see what can be done to improve it.
