rigbymauser:
You may not believe this, but the Greener 'Empire' 12-bore has a wider and heavier standing-breech than the 10-bore Zabala.
Those Zabala shotguns get their extra overall weight from a billet of steel in the butt-stock (at least, the ones sold in Australia a few years ago did!). One would assume they are equally strong (or stronger?) though, because of modern steels.