Hawken rifles, manufactured in St. Louis were made as flintlocks up until 1834-35 when the caplocks became the "newest" and more efficient way to go.
There are no known flintlock Hawken rifles.
1816 US Military Muskets were converted to caplock asap.
When Jacob Hawken arrived in St. Louis in 1818, the town was still a tiny fur trading outpost on the edge of the wilderness. St. Louis was just starting to be known as the logical supply point for people headed west, due to its excellent location along natural overland and water routes. Hawken came to St. Louis from Harpers Ferry, Virginia (today's West Virginia), where he, his father and brothers were gunsmiths in the federal armory. It is probable that Jacob learned his gun-making skills during his years in the armory, skills he brought to St. Louis in 1818. A commercial hub such as St. Louis provided Hawken with the supplies he needed to repair and manufacture firearms. Hawken befriended James Lakenan, another local gunsmith, who, according to local records, operated a shop at the corner of Hickory and First Streets — about one block west of the Mississippi River levee.
During the early years of Hawken's St. Louis trade, he made rifles with the flintlock ignition system, later converting to the new percussion system in the 1830s. Hawken manufactured a larger caliber weapon, different from the popular "Pennsylvania" or "Kentucky" rifle. These rifles were not powerful enough to kill large western game such as grizzly bears, bison and moose, whereas the Hawkens fired a larger ball.
Unfortunately, only one known example of a Hawken flintlock rifle has survived. This was made by Jacob's younger brother Samuel, who operated a gunsmith shop in Hagerstown, Maryland, and later moved to Xenia, Ohio. This full-stock Hawken flintlock is believed to be a pre-1825 model. It bears the trademark "S. Hawken" on the barrel, and is currently in a private collection.
Springfield Armory states the conversion of the 1816 musket took place in a 12+ year period starting in the late 1840's as a result of the excellent performance of the Mississippi Rifle in that conflict. 12 yrs is ASAP in glacial time.