Ak-112 from the original games it will have low-ish damage with a very high fire rate and respectable accuracy 5mm ammo
R-91 from fallout3 5.56 ammo
Remington 870 to provide middle ground between the double barrel and combat shotgun.
A 1911 pistol to shoot .45 ammo (with a mod to change ammo to 10mm)
And a M16A1 short barrel and stock will change it to a model 607 5.56 ammo
Last but not least a 9mm mauser and a .38 revolver
Also worth mentioning that like the vanilla weapons all of these Will be semi-automatic with out mods
Any thing else I should add or know?