RE: Best calliber for grouse
"The shot absolutely destroyed the bird with nothing much left to eat."
I shoot 12ga all the time and never seen that at thatdistance. I like 12 because it give just a bit more. I shootan O/U that is almost as light as 20's. Beretta is my gun of choice. Light and relieable. However, shoot whatever is comfortable. That is what's best.