Do Not shoot shotgun slugs out of anything but a Improved Cylinder ( IC ) or maybe a modified barrel. The slug's diameter is larger than the Full choke barrel, so the slug would have to squeeze out of the barrel which could blow the barrel up.
I've shot foster style slugs out of many a full choke barrel and never had a problem. The lead slug is very soft.
However with screw in chokes I would used IC or Modified.
From the OP's post he wants to load slugs, then buckshot. I'm guessing slugs for first hit, then buckshot on running pigs. Try some of the buffered buckshot loads, Flite Control wads, or low recoil rounds, they pattern pretty well with most any choke.