[buwaya]

The British also had some German rifles that came with their mercenaries, as part of the usual German-state force structure.

And the American loyalists doubtless had some riflemen as well.

Rifles had some use on the battlefields, but the vast majority on either side used muskets, including the American militias. The musket was much more convenient and faster to reload. Indeed, on numerous battlefields the decisive weapon was the bayonet. The American revolutionary armies were often defeated by the British infantry advancing firing vollies, followed by the bayonet. For the first few years of the war the Americans were defeated, on the battlefield, with depressing regularity.

[libstripper]

“The British also had some German rifles that came with their mercenaries, as part of the usual German-state force structure.”

The big differences between the Jager rifles of the Germans and the American rifles were the longer barrels of the American weapons and the use of patched balls in the American rifles. The greased patch would hold the ball and occlude the grooves of the barrel, enabling the ball to be loaded much more quickly and giving the ball the necessary spin. I have a replica Kentucky rifle; it takes me about a minute to load and prime it, a lot slower than with a smooth bore.

[Chainmail]

Yup. But the question involved Breech-Loading rifles - and like I said before, I'm only aware of the British breech-loading Ferguson Rifle fitting that description.