You won't know until you shoot it and compare the chokes with the same exact load and lot #. I tried a .665 Indian Creek BDS choke for the very first Indian Creek choke. It was terrible. Shot like both Jelly heads I tried with the 7's at about 200 shot in the 10" at 40yds taped. Then I tried a .655 and it did about 255 in the 10". I then tried the .668 and you can see that pattern above. Nite and day difference between the .665 which was only .003 bigger in exit diameter which is odd. But it is what it is. Then I tried a .675. Not as good as the .668. I honestly believe a Indian Creek .670 choke to .675 is just about idea for 28" barrel 870. But that may just be my barrel.