In Rising Storm 2 the American troops, in both the Marine Corps and Army factions have access to the Ithaca M37 Shotgun in 3 variations: the Trench Gun, The Stakeout, and The Duckbill. My personal favorite of the three is the Trench Gun, particularly because you can often get head shots by aiming center mass. The conical spread tends to work in your favor one-on-one. While the Stakeout also has a conical spread, you can't aim down the iron sights directly due to a current game mechanic; dramatically limiting its medium range potential. Rising Storm isn't like Battlefield or Call of Duty. One shot is often enough to do the job, and that includes pistols.
Hope you enjoy!