I have one for 20ga win/inv chokes it's .560 and it will be my go to in my setup. Spent some time with it last spring at the patterning board. I was shooting Fed HW 6 and the original Rem Hevi-shot 6, bought a case from Dunn's when they were clearing them out. I have some Fed HW 7's but didn't get to shoot them. I liked the pattern my gun was throwing with the Rem Hevi 6's at 40yds with this choke. I've never been big on counting numbers, I look for a nice even pattern with no big holes in the pattern at 30 and 40yds. I also ran those loads throw a Truglo in .565 and Tru Choke in .570 for comparison. The Feds weren't bad in the 6's, the Rem Hevi was just more to my liking. I hope to try some mag blends and the Fed 7's this spring.