Grouse are fun.
The scare the crap out of you as they fly away.
I have hunted them in NY, Ohio, PA and Id.
We used shotguns in all the eastern states but used 22 pistols in ID.
Found shorter fast swinging guns work best. I like 7.5 or 7's as shot size
and the Grouse will wait till you are ducking under a branch, climbing over a log or some other thing that has you way out of position to shoot till they fly out from under your feet wit hthe loud drumming beating of their wings.