As I grew up in the Midwest taught by my father, and taught again in later life as a lifetime cop, it was always revolver and pistol, both being handguns.
"Revolver" explains itself. I was taught that "pistol" explained the auto-loading function as powered by the exchange of gasses and the employment of springs. indeed, a CO-2 powered pellet gun may fall into the firearms category if the velocity pushed it above a certain FPS limit which is different state to state.
BTW, handguns were handguns...Firearms. All "firearms" we're either handguns, or, long guns.
Firearms...Until pointed at another person with malice. Then both were weapons, but not until so applied. Even with the "accidental/unintentional" discharge investigation, the firearm remained a firearm until malice could be supported.
If you say "pistol" to me, my brain sees a semi-automatic handgun. Usually a 1911 design, because that is what my father trained me on. If you say pistol and show me a Colt Python, I'll think you need a lesson in nomenclature and when time permits, I'll open that exchange of thought.
I was an FTO cop for 8 years, and a Sergeant cop for 18. There is a lot, I mean A LOT of cops who learned to see it my way.
That's my story and I'm sticking to it.
Y'all be safe.