Just ordered an IC BDS choke for my sons 870. Was wondering what to with Hevi 6's or Mag blends or 7's.
It sort of depends on the choke size for a good answer. If it is a 555 definitely the hevi 7s, 560 -570 , perhaps the 6s or even the 7s again, 575 the Mag Blends and or 6s most likely, but this is not an exact science by a long shot.
As barrel length and choke diameter are not given it is harder to guess. Only the true test of putting the shells through the gun at a given yardage will tell for sure. The only other variables are the lot#, wind, humidity, elevation, temperature, shell components, .........etc.
Good luck with your recent purchase.
The IC .555 will through good patterns with all the loads you listed, but you are going to like the 7's the best if you are counting the 10"
I would stay with something in the .570 range,it seems to do well with alot of different shells
I like the 555 with 7s !!!