My thanks to all who provided comments.
My collecting has always focused on military antiques, as has the knowledge of experts to whom I've shown this pistol. Most of them date the pistol at 1790 or later but admit that some of its features go back to an earlier time.
I have very much wanted the pistol to date to the time of the Revolution, since I have its history (from the family) going back, generation-to-generation, to Lieutenant Abraham Randall of Stow Massachusetts. Randall fought at Concord as a Private; but he was quickly promoted to 1st Lieutenant and served at various engagements in New England throughout the war.
Having read all your comments, I understand that the dates at which feather spring rollers first appeared varied between the continental gunmakers and those of Great Britain. It also seems that Militaries were slower to adopt innovative technologies than was the civilian market.
Lieutenant Randall came from a wealthy family who had immigrated to New England long before the Revolution. He was a man of considerable means and could have easily afforded to purchase the 'latest and greatest' pistol technology available. As an Officer, he was likely mounted at times, and could well have chosen a horse/saddle pistol.
Thank you so much for your responses. If anyone has decisive information that supports (or refutes) my biased hope, please comment further.
Harvey
PS: Regrettably, this is not a pair of pistols, but only one. I accidently posted two full-length photos and could not discover how to delete one of them. Sorry for the confusion.