Fat? Do you mean from the top and bottom views? If it was any skinnier, it would look kinda lousy. Also, here's kinda' what I was aiming for.
Without the wider piece at the end of the barrel, though. Maybe it would look better with it? I tried to make the bolt-action lever-handle visible, but it wouldn't show up well, so I scraped that. Also, shotguns and rifle look a lot alike in most cases, but the difference is that shotguns usually have the pump-action piece and the double barrel or 'sliding' rod.