Just went to the range today with a relatively new Savage 220. Tried out Hornady SST's, Rem Accutips, Federal Copper whatevers (new round, I think), and Winchester dual bond (first 2 in 2 3/4; last 2 in 3 inch). The SST's performed the worst, didn't group well, the others all performed well enoiugh, I'd say the Accutips were best (but I've heard they have penetration issues??), The Winchester's probably next.

I also have an 870 with a slug barrel (12 gauge) that SST's didn't perform well out of. Performance improved dramatically with Rem Copper solids, which are a much slower round than the SST's. In my opinion, if you are having grouping issues, try a slower round.