I'm going to assume we're talking about 12 ga...........
Rifled (Foster/Brenneke) slugs go somewhere in the neighborhood of an ounce, give or take. Roughly 400 grains (edited, was half blind from lack of sleep when I posted that
)..........
Sabot slugs go somewhere in the neighborhood of 350-400 grains IIRC.
Sabot slugs for rifled barrels, Rifled (Foster/Brenneke) for smoothbore.