They'll probably use Moritas, it's the general name for all the rifles in the Movie and TV series.
It might be that there's special grenade launcher ammo called Flechette ammo, which is basically shooting bunches of toothpick-like barbs similar to a shotgun.
The morita isn't a complex gun, so it could probably be mass produced on a Fed occupied scale rather easily.
It'll be interesting how they differentiate the core and cap troops. Cores have much lower resiliance (lower target, hit, and kill stats) but it seems like they still use the same 2xd6 rifle and there's a lot more of them. So, they could probably put out a big wall of fire, but without the mobility of jump packs, once the bugs close in things get really ugly.