Actually, the premise of your question is flawed.  The colonists preferred smoothbore muskets for close-combat situations precisely because they could be reloaded more quickly than rifles, thus allowing more shots at close range.  This was due to the fact that the ball had to fit more tightly into a rifled barrel.  The ball had to be wrapped in a greased patch and almost hammered into the rifle bore, which became particularly difficult after the weapon had been fired several times due to the accumulation of gunpowder residue in the bore.  That is why rifles did not come into widespread use as a military weapon until the mid-19th century.