Idaho allows rifles for grouse hunting as well. .22 handguns are great, but then so are very light cast bullet loads for the big game rifles when regulated to shoot to point of aim at 25 to 50 yards. We use either light cast bullets or round-balls for grouse loads.
115g FNPB cast for the .30 caliber rifles
165g FNBB cast for the .35 caliber rifles
.375" lead round balls for .375 calibers
.435" lead round balls for .44 calibers
.457" lead round balls for .45 Rifle calibers
Fun stuff! And another load to develop for the hunting rifles.
Beartooth: A Bullet Worth Waiting For!