Tinker the only Swiss powder I've shot was ready made 10 ga. ammo from Metallic Cartridge Co. several years ago. When I pattern my guns I clean between shots (usually a few wet patches of alcohol followed with a couple of dry ones).

The ammo I load myself for my 10 and 12 ga, shotguns has been with Goex FF.
Goex seamed cleaner than Swiss between shots, might be because I use a lubed cushion wad from Circle Fly.
I did cut one of the Mettallic shells open I can't recall if he used a dry wad or not..I do remember Swiss is some strange looking black powder.