Smooth bores aren't very accurate. The Pennsylvania/Kentucky long rifles which were owned by civilians were far more accurate and lethal. Many of the minute men carried such firearms. A short history of the rifle in America can be found here.

"Col George Hanger, a British officer, became very interested in the American rifle after he witnessed his bugler's horse shot out from under him at a distance, which he measured several times himself, of "full 400 yards", and he learned all he could of the weapon. He writes: "I have many times asked the American backwoodsman what was the most their best marksmen could do; they have constantly told me that an expert marksman, provided he can draw good & true sight, can hit the head of a man at 200 yards."