Briefly, TSS is available, but not in a loaded shell. Hevi13 #7s approximate lead #6. Heavyweight #7s approximate lead fives. If you can stand a full house 12ga load Hevi 7s are good, but you need a choke. If you are interested in not using a special choke, using a light 12ga load or going down to 20ga, you want Federal Heavyweight 7s.
I used to use a 3 1/2" 12ga with lead 6s. Inside forty yards, my 20ga with Heavyweight 7s works just as well. I mean it just poleaxes them. Having killed three of my last four with the 20, I don't even own a 3 1/2" gun anymore.
