Yessss… my videogame instinct craves firearms of ridiculous proportions. Though since shamblers are drawn to gunfire I’m thinking that one shot from a behemoth like that might bring an entire city down on you.
Oh also, revolvers in .410 and .45 long colt and on rare occasions .454. That’s because all these calibers fit in the same size receiver. There’s a fair number of manufacturers that make them and they seem to be fairly popular at the moment. Google .410/.45 to see quite a few examples.