Grouse are not as dumb as some people believe. A well hunted grouse, or grouse in an area of huge hunting pressure, they take off at the sight of a vehicle, UTV or quad. When the grouse are pressured, one is lucky to get 50 yards away. That 10-30 yard rule is no longer possible.
Back in the late 1990's, I guided for Kettle River Outfitters in Christian Valley. We had hunters from Pennsylvania, apparently their state grouse are so spooky, they take off at 100 yards away or even farther in some instances. The hunters stated the grouse were tougher to hunt than their WT Deer. When I had them shoot grouse with a Ruger 10/22 at those 10-30 yards distances, they enjoyed this more than shooting their WT bucks.
Grouse that are not hunted, can actually be harvested with a rock or slingshot. I would like to see a hunter try this in Pennsylvania!......

LOL