Not really sure. That shell was built for the Federal shells wasn’t it? Could always try Long Beards or HeviShot.
x2. I do not shoot an 870 (yet, looking to possibly add one to my stable) but the Longbeard XRs seem to always pattern well no matter what choke you use. I have used Hevi shot and while I like it, it just costs way too much for me. I have used HEVI #6s, HEVI Mag blend (I believe it was 5,6,7 blend) and HEVI#7s. Hevi 6s were ok. I do not like the MAG blend as different boxes seemed to pattern different for me. The HEVI 7s were GREAT but again just cost too much. They gave me similar patterns out to 45 yards as the longbeards did BUT they gave me better patterns at close ranges like 20 yards than the longbeards. The longbeards are WAY cheaper so I chose the longbeards since they pattern well enough.