The Desert Eagle Mark XIX appears as the "SOP38 Pistol". Holds 10 rounds in the magazine and can be dual wielded after learning the necessary skill. It is pretty useful even in the later parts too because the game throws lots of weak trashmobs at Sam at later levels.
Mossberg 590
The Mossberg 590 with wooden furniture and pistol grip appears as the "Single Shotgun". Unlike the pump shotgun in BFE, this one no longer needs to be reloaded only pumped after each shot.
The Fostech Origin-12 appears as the "Autoshotgun". It is classified as a heavy weapon and does not share ammo with the other two shotguns.
M1928AC Thompson
Appears as a skin for the M29 Assault Rifle.
AKM
AKMs are used by Michelle and other French resistance fighters.
Mk 18 Mod 1
A Mk 18 Mod 1 appears in the game as the "M29 Assault Rifle." It uses the same shared asset model from Virtual Warfighter and earlier versions of H3VR. It comes with 80-round magazines.
Hand Held M134 Minigun
The Hand Held M134 Minigun, a Serious Sam staple, is present, referred to as the "XM214-A Minigun."
Barrett M107
The Barrett M107 appears as the "RAPTOR 16mm Sniper Rifle".
GP-25
The GP-25 is an unlockable attachment for the Mossberg 590, because it is 2020 and the new Serious Sam game has to have weapon mods, side quests and a skill tree.
Basic, low detail M230 Chain Guns are visible on the Technopolyp Helicopter enemies, which are basically Apaches infected with some off-world parasites.