Snake's main weapons from both John Carpenter's Escape movies:
The Mac-10 with the two-stage suppressor and the superfluous rifle scope
And the 'Coreburner' LeFrance M16K.
They're both stupid and over-the-top, but come from one of the best action movie series of all time.
The Coreburner probably isn't even that hard to make in theory, just a lot of custom parts slapped onto a bog-standard AR, if that's the route you want to take.
And when Gaston tried to put his own own AARP abortion round on the market to the response of crickets from agencies and laughter from everyone else, Springfield had one of their Croatian imports chambered for it on the market before Glawk's own tupperware blaster was made available.