Colonial Marines
Some weapons and uniforms from Aliens. Threw in some Weyland Yutani stuff for good measure.
The Weyland-Yutani stuff is available from cities and outposts while the USCM gear is at military bases.
I used the pretty tight EK Armory mod as an example. https://steamcommunity.com/sharedfiles/filedetails/?id=1769403760
The Ithaca m37 should be able to use the shells from EK Armory, too.
