"This thing is inspired off those Jakobs revolver sniper rifles from Borderlands. The parts were modelled off the Springfield M-1903 (the front part), the Smith and Wesson M-29 revolver (pretty much the entire middle part), the MTS-225 shotgun (The stock) and the M-14 for some small parts that you won't even notice.

Why give it that name?

Well there's a very similar weapon from Counter-Strike: Nexon Zombies called "Savery", which was frequently used to "babysit the unique minded" in the GPD server. Basically this is just the same gun chambered in .50 cal instead of .308 or whatever it was originally chambered in."