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.
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.