There are some perks in Fallout: New Vegas that boost performance of one-handed guns, for example:
"While using a pistol (or similar one-handed weapon), your chance to hit in V.A.T.S. is increased by 25% […]"
"The Run 'n Gun perk reduces accuracy penalties with one-handed ranged weapons (Guns or Energy Weapons) while walking or running"
The sawed-off shotgun behaves like a one-handed gun in-game (full movement speed when drawn, holstering on the hip, etc.), so it should qualify as one-handed weapon similar to a pistol, but it is not in the list of weapons affected by Gunslinger(the variant from FO3 however is). The Run 'n Gun article isn't very detailed either.
Question: Is the sawed-off shotgun exempted from those perks (despite qualifying), or is it missing from the Nukapedia articles?
Best Answer
The sawed-off shotgun is both a shotgun and one-handed gun. Even though there isn't a Wikia article on one-handed guns you can use the Jury-Rigging perk page as a reference of one-handed guns. The perks listed above should affect all one-handed guns, which the sawed-off shotgun falls into.
In this case it appears the wikia article is incomplete. The weapon should be included on the list of affected guns.