For the first 25-30 years of hunting ducks in the fishing village where I grew up, all the older gunners used nothing but what they considered the "best" of shells: premium-priced, high-brass 12 gauge CIL (Canadian Industries Limited) Imperials---"Blue Imperials" they called them because of their royal blue colour. They made no distinction of the guns they used them in, twist, damascus or fluid steel. As far as I know, they still don't.