If you are going to a National Park (and maybe CA state parks?) the shotgun is illegal. Not just unnecessary, but Illegal. The only place you could use this is in a national forest during hunting season--and expect to get a TON of grief from fellow campers if you decide to spend the afternoon making really loud noises in the pristine wilderness.

Most people go to the mountains to get away from noisy neighbors. I do. And if you were shooting a shotgun off where I could hear it, I would find a way to let you know about it.