As many people here will know the
Ferguson Rifle was an early breech loading rifle used in small numbers during the American War of Independence. It was the brainchild of
Major Patrick Ferguson who fought and was killed in the ARW.
The rifle itself was only produced in small numbers, about a hundred, and probably has had a bigger impact in fiction than in real life. The main causes for it's failure being that it was expensive and difficult to produce compared with contempary weapons like the Brown Bess, and it was less sturdy in action. These factors combined with Ferguson's death led the rifle to dissappear from use before the end of the ARW.
However what it Patrick Ferguson was not killed in 1780 but survived the war and continued as both an officer and a rifle designer?
While the Ferguson Rifle won't make much of an impact on events of the ARW, (unless some important historical figure is shot by one and that's outside the remit of this thread), but presumably Ferguson will keep working on the thing and eventually price will go down and reliability go up. Perhap even enough for it to be used by British light infantry in the Napoleanic Wars, maybe even replacing the Baker Rifle.
Perhaps the greatest effect of an even reasonably successful Ferguson Rifle would be on British military thinking about breechloaders. In OTL the British Army didn't get a breech loading rifle until the Snider-Enfield of 1868, but perhaps seeing the effect of even the flawed Ferguson system will spur the British to look into and develop a more reliable weapon of another design during the first half of the 19th century?