I remember reading that being a case with the old K-frame revolvers like the Model 19, because on some models the bottom of the forcing cone was much thinner than on the other sides, because of relief cuts for the cylinder rod. But then metallurgy was different back then. I don't know about the subject today. Edit: Ugh, now I've depressed myself. One revolver I wanted more than any other was the Classic Model 19, with 4" barrel and target style walnut grips. But because of the forcing cone issue I abandoned that desire.