I prefer #7 1/2 to all others but when the wind starts blowing and the late season rolls around I switch to #6. When the leaves are gone and the visibility is wide open grouse will flush further away from you. Sometimes the only shot you can get is 40 yards or so.

I would hedge on #8 and go to 7&1/2 also. And "high brass" meaning plenty of powder charge

6's are the best for a clean kill

7 1/2s work well until the later season when i switch to 6

I like #6 shot because it will carry its energy better than smaller pellets, giving a cleaner kill.

#6 , #7 1/2 ,#8 .
Good hunting!

Good Link 2Poppa and + 1 for you sir!!!