There’s a few firearms I’m actually surprised haven’t been added yet, seeing how thorough it’s been thusfar. Mind, I’m not exactly going to be heartbroken if these don’t get added or anything, I just think they’d be interesting additions.
Thompson Submachine Gun: Okay, I know firearms have been shot down for probably being out of date, but considering how iconic the Tommy Gun is (and the fact we’ve got working cap-and-ball firearms in the game), I’m surprised it hasn’t made its way in (granted, if only as a museum/mansion piece). High-capacity 50-round drum (for balance, I wouldn’t go with 100) and reasonable-to-good burst fire rate (don’t know how burst size is decided here), but with an extended reload time (the drum magazines were notorious for being slow to change) and rather hefty recoil. Also, it weighs 10.8 lbs empty, so it’s pretty heavy.
Daewoo USAS-12 / Atchisson Assault Shotgun: This got brought up by JamesR3d above (albeit as just a list of guns), and I think it deserves a second look. Right now, the only fully-automatic shotgun we have is the Rivtech Autoshotgun, and that only uses 20x66mm Caseless. An autoshotgun firing in 12-gauge is a niche currently left empty. You’d be looking at a gun with 10 / 8 round magazines and a 3-round burst (based on the Rivtech one). Compared to other shotguns, you’d have reduced damage (the USAS-12 technically only takes 2-3/4’’ shells, and both have short barrels), elevated dispersion (short barrels again), reduced recoil (for a shotgun anyway; both are built to absorb recoil, and both are rather hefty), and reduced range (those short barrels again). The former weighs 12lbs, the latter 11.5lbs. Basically, they’d be able to put out a rather alarming amount of damage in a short time, but would overall be rather ammo-inefficient. The plus side is that, in single shot, they’d actually be more managable in terms of recoil (although if you’re using a shotgun, recoil is probably pretty low on your list of priorities).
Skorpion vz. 61 E: I mostly bring this up, because it strikes me odd that we have the .32 ACP ammo for a grand total of one handgun (however iconic). Depending on how you want to classify it, the Skorpion would be either a Submachine Gun or a Machine Pistol in .32 ACP. Tiny, light (1.8 lbs). I don’t quite know enough about how stats are quantified here to take a stab at how it’d add up (especially since it’d be getting compared to a handgun, stat-wise).
M134 Minigun: The absence of this one initially caught me by surprise, although thinking it over, I get why it was omitted as a personal firearm. Still, I’m surprised the venerable Minigun isn’t available as a turret for vehicles (or, more evilly, as a hostile enemy… although, then again, getting splatted by a turret cranking out just under 67 .308 rounds per second might not be some people’s definition of fun), with perhaps a crafting modification to make it possible (albeit not all that practical) to carry and fire, powered by UPS.