THAT is gonna be one SERIOUS Moose gun!
You guys scare me: I thought I had some big guns, but a single 11, a double 11 cartridge gun and a double 10 sort of pale into insignificance when confronted with 6s, 8s and 9s.
When I lived on Fogo Island, there were still a few old guys hunting with their 'three-quarter' and 'seven-eighths' guns: generally anything up to about a 6. They knew the things were legally classed as 'artillery', but how else do you do a 75-yard shot on 50 or 60 birds? They were about EATING during the Winter, not about 'sporting'.