ivory and rifles

[Booth, Curtis]

General George S. Patton disdained wussy pearl for pistol grips. His
revolvers' handles were clad in soldier-worthy ivory. He is reported to have
said (but maybe just in the movie), "Only a pimp in a New Orleans whorehouse
or a tin-horn gambler would carry a pearl-handled pistol."
I always thought the difference between a gun and a rifle was that a rifle
had to be rifled, whereas a gun wasn't. It wouldn't make any sense to rifle
a shotgun, would it? I don't know about guns (or rifled arms) too big to
hold in the hands, however.
Curtis