This Old Gun: U.S. Model Of 1842 Musket | An Official Journal Of The NRA
By the latter part of the 1830s, most of the major powers finally let practicality overcome economy, realizing that it was time to switch their small arms over from flintlock to percussion. Britain and France were among the earliest, with the United States following suit in short order—the Americans fielding the handsome Model of 1842.
Source: americanrifleman.org