Similar pistols are shown in Battle Weapons of the American Revolution, by G.C. Neumann. You might look a pages 252 (French cavalry), 264, 267 and 272. The last three are American. The triggerguard tang on your pistol shows French influence, as alexsnr suggested. Kinda like a "Type D" tradegun", which only means that an American made it.
In my fairly ignorant opinion, I would call it a cavalry weapon/holster pistol, likely Revolutionary.
There is an rather arbitrary, but commercially significant, distinction made between an English style holster pistol, made in America, and a "Kentucky" pistol, made in, say, Pennsylvania by a guy who also made rifles. For discussion of this you might want to look in Norm Flayderman's Guide to Antique American Firearms...and their values, 9th Edition, pp671-672
I had occasion to look over such information a year or so ago when I bought an American (I think) holster pistol, civilian, circa 1760.
My, l do like your pistol!
Butternut? Usually thought of as a Southern wood, personally do not know how far north it was used.