I have a 12 gauge Remington Model 1100 chambered for 3" magnums. While it easily shoots factory 2 3/4" shells, I need to remember when reloading shot shells to put a heavy-enough powder charge in it to eject the spent shell. If you are looking to grouse hunt, I'd go with the scatter of a 12 gauge and the quickness of a semi-auto for that second shot.