I assume you are refering to Hawken rifles made by Samuel and Jacob Hawken in St. Louis, and not earlier Hawken family member guns made back east. Since Samuel arrived in St. Louis about 1818, and older brother Jacob about 1825, they obviously made flintlock rifles during their early years in St. Louis. But if you are considering their early "trademark" style double keyed plains rifles in early flint, I doubt that style showed up until the 1820s, well after the 1800 date you mentioned. Of course, other Hawken rifles were made before 1800 back in Hagerstown, Maryland, but they were Kentucky sytle rifles, not plains rifles. Hope this helps. Shelby Gallien