The only time I can ever remember using a barrel selector in the field came on a preserve hunt I went on with my Miroku Charles Daly, a gun that has the typical barrel selector combined with the safety. A pheasant flushed. I shot it and opened the gun, ejecting the empty. A second bird flushed before I could reload. I closed the gun, selected the top barrel with the safety switch (the top barrel was the only one still loaded. Closing the gun had reset it to shoot the bottom barrel first), took the safety off and shot the pheasant.