The SBS is a two-shell double-barrel shotgun that hits hard up close. Its unique The True Loyalist comes from a treasure hunt, and it also appears in Vaas: Insanity.
Two big shots at close range, then a reload. It works for ambushes and finishing a target fast, but leaves you open against groups.
It takes buckshot, standard shotgun, poison, blast and incendiary shells. Incendiary shells add fire damage to targets you do not kill outright.
1887
The 1887 is a lever-action shotgun with a seven-shell tube that you can extend to ten. It deals solid close-range damage but works the action slowly, so it rewards careful shots over panic fire.
1887 Sawed-off
The 1887 Sawed-off is a cut-down lever-action shotgun built for hip-fire at point-blank range. FND Vanguards, Engineers and Special Forces Snipers carry it, and Rodolfo Claudia's insurgency rewards its unique Bases Loaded version.
KSG
The KSG is a semi-automatic shotgun with a 15-shell capacity, so you can keep firing in a close fight. Buy it from Juan's arms dealers, or get its unique Excavation Execution from The Long Drop treasure hunt.
M133
The M133 is a pump-action shotgun that can drop most unarmored or lightly armored soldiers in one close shot. El Rubi is its unique version, built by a Yaran furniture maker.