I run a .570 High Voltage in my 870 with a 21" barrel and Federal TSS. It throws a heck of a pattern. The same choke in my Affinity with a 26" barrel is too hot for me (380 in a 10" circle). I would like to try a .575 High Voltage in my Affinity, and may yet....
According to Jebs, same choke just different appearance and constriction...