This only applies to a firearm that is purposely manufactured as a "handgun" - meaning a revolver, break-action (derringer), or semi-auto pistol. While an AR pistol is manufactured as such, their size and unwieldiness make them a mote point, of course.
It would not apply to a short-barreled shotgun - break-action, pump, or semi - as those are originally manufactured as shoulder-fired guns.
It wouldn't apply to the short barreled PISTOL GRIP ONLY guns (that were originally built that way, never had a stock), because they are designed to fire multiple projectiles. The Oklahoma statute makes no mention of having a stock or not, or overall length on either the definition of "Shotgun" or "Sawed Off Shotgun".
The OK statute defining firearms is written horribly. In my not-so-humble opinion. I pretty much facepalm every time I read "Sawed Off Shotgun" as a legal definition. Stupid.