I wanted to see just how accurate my SS was, so I bought about a dozen different kinds of target ammo, and tested those against a bunch of different kinds of regular ammo.
Then I shot five 5-shot groups from each box.
Some target ammo, like Winchester T-22 and CCI Green Tag, didn't group well at all. Most of the fancy, expensive European target ammo (Eley, Lapua) didn't do all that well, either.
But Federal Gold Medal Match 711B makes dime-size groups in my basement range (about 25 ft.). Federal Gold Medal Match 900B shot well, too.
For just regular plinking cheap plinking, I use RWS Sub Sonic or CCI Standard Velocity.
So my Single Six eats a lot of lead round nose bullets, but rarely sees a copper plated one.