GOBBLING BUCK., I HAVE A 835 ULTI-MAG ALSO WITH 24 INCH BARREL I HAVE TESTED LOTS OF DIFFERENT LOADS AND CHOKES AND THE ULTI MAG FACTORY CHOKE THAT COMES WITH THE GUN WORKS THE BEST, I USE WINCHESTER 2 OZ 3 1/2 HV 6 SHOT . HOPE THIS HELPS.