Ed, Shooting Facts & Fancies by Gough Thomas covers the subject. He wrote from the perspective of an experimental engineer. His concluding paragraph on the subject reads:
'So, a gun slightly pitted, and throwing, maybe, slightly wider patterns than it otherwise would do, may yet prove the better gun for work at moderate range. But the ideal is still the immaculate bore, throwing patterns of the best possible quality, of the highest attainable pellet energy, and of the right spread for the work in hand. As we press for longer and longer reach, the nearer we can get to the ideal the better.' Lagopus.....