Have SSX .643 for my 870 and going to try Hevi 13 3/2/6's and 3/2/7's. Should shoot ok considering that it holds the world record with the Hevi 13 3" 2 ounce load. Like those odds of getting decent patterns. I have found that I am able to turn 200+ out of several chokes I have tried in the .655 to .665 range with Win Lb 6's. Kicks, Ventilator, Indian Creek, Hevi 13 Choke etc..just don't care for softball size patterns at 20yds. To each his own.