Guys, Thanks for the information. I love this site for the depth of knowledge of so many of its participants. It seems as though Browning would have modified their bore measurements in the late sixties to compensate for the wider usage of plastic hulls and power pistons, but I suppose ammunition worldwide did not change as quickly as it did in the U.S. This explains why the two Superposed 20 gauges I had seemed to powder claybirds so well.Anyway, thanks very much for the replies. Sandlapper