Ron,
While some hunters used buckshot before the war, while I was there it was not legal on cloven hoofed game. Slugs were legal and were used. How they were loaded depended on the type of hunt and tradition in the local area( used in areas with woods and pigs/Red Deer; not as much in areas with fields, small game. If loaded in left barrel, the slug could be fired with rear trigger w/o changing the barrel selector. As long as it was safe, I don't know of any rule on how to load the drilling(ie other hunters wouldn't like it very much if the rifle was loaded in a circle drive).
Mike
