I don't doubt it but it would've been on a very small scale. In the Revolutionary War, the British also had a few breech loading rifles.
One of the dedicated rifle regiments that were formed after the Revolutionary War, was the 60th rifles which was originally raised as The Royal American Regiment
I am dubious about a rate of fire of 6 rounds per minute - Wiki doesn't mention the source
You say a rate of 7 RPM was not "unheard of" - well then, please post a reference to this "not unheard of claim" (I note that the only real evidence you have for the RoF was a YouTube video showing at best a rate of 4 RPM)
This webpage gives a rate of
4-5 rounds (and the 5 RPM must have been in ideal conditions, by a highly skilled solder, without the stress of the battlefield)
redcoat reenactors in Boston
footguards.tripod.com
Remember the doctrine was of volley fire, so a soldier fired at the same rate as the rest of his company.
Let me know when an American can do this.
Oh and would it also be a "problem" is a Brit was to know that the M-4 Sherman tank was a "medium" tank, when the American thought it was a "light" tank ?
Don't rely on Wiki too much. Check their sources first.