Guess I'm just old school. I hike for grouse, following my shorthair, carrying a double gun. Shoot them on the wing only. You know, the way a sportsman does it. If they make it to a tree they get a pass.
The whole idea is to harvest as much meat as possible and ensure a clean humane kill. That's the sporting ideal.
Shooting grouse with a rifle (I myself use a .22) can be very sporting as you are trying to hit a target the size of a 50 cent piece and the result is usually either a instant kill or a clean miss. Up here if the grouse flies, they're usually in the thick bush in a second and effectively screened from a direct hit of bird shot so if you intend to get any birds at all without the advantage of a bird dog, head shots with a rifle (or pistol) is a viable as well as a sporting way to do it.
You don't find it sporting - I do and apparently the hunting regs do, so we'll have to disagree on that point.
I would also much prefer a head shot grouse as opposed to a pellet ridden grouse body any day. 
