Dang Redrum:
you've been busy since we last crossed trails. I did a number on my arm like that once when I was a kid. I was swinging an old L.C. Smith up onto a goose and the butt slipped off my shoulder just as I fired off one of the barrels. Well except for the bruise it looks like you're off to a good start with getting your guns and gear together. There are some posts waiting for you over at the Ruger forum and the FFF. Jump on over to the CAS section there, we've been trying to get that part of the BB jumpstarted. I'd follow that advise and not be shootin any heavy loads in that blunderbuss for a while.
Mike