Scroll guards do not predate 1820 here in the States as far as I know. They were first popularized on English shotguns it seems. Some of the earliest Hawken Rifles with scroll guards have the “shotgun type” with integral fore and aft extensions. So does the Philip Creamer Clark Rifle I believe. On later better quality plains rifles the guard was affixed to a long trigger plate not the stock. The Scroll Guard trade rifles dated 1830s and beyond I believe, can check.