Sorry my question wasn't clear. I was specifically asking about the barrels and not the ribs. I was referring to when the barrel increases a bit in diameter again at the very end of the barrel. In some guns this can be an exagerated flare. However even a small flare at the end would add just the slightest bit of weight and supposedly add speed in settling on a target and smooting out the swing. On barrels shorter than 26" my thought is it wouldn't make much/any difference. But anything 26 and longer it may help. I ask because I recently used a custom O/U that was built for doubles trap and it had swamped barrels. It seemed to make quite a bit of difference on swing and follow through. Anyway that just got me wondering if it had any application. I figured somewhere along the way someone probably already tried it and it was either dropped because it wasn't much/any better or it just made the gun look hideous

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Bill