There's 4 shotguns, I think. Shotgun, Sawn-off Shotgun, Enforcer Shotgun, Combat Shotgun.enforcers shotgun/ (vanilla) combat shotgun have identical stats, but a different name
enforcers boltgun/ (vanilla) boltgun have different ammostats next to their different names
Reading the weapon ammo stuff, I think, at least in the book of peril, it's pretty clear that shotgun ammunition is any type of shotgun and bolt ammuniton is any type of bolt weapon and so forth.
Book of peril
under shotgun ammunition says
"The following types of ammunition can be purchased for use in any shotgun, combat shotgun or sawn-off shotgun."
And then it lists the plant buster, phosphor and rad shells.
And then in the bolt ammunition, says
"The following types of ammunition can be purchased for use in any boltgun, bolt pistol, heavy bolter, or any combi-weapon that includes a bolt weapon component."
And then it lists the gunk bolts.
And you have the Auto weapon Ammuniton
.