This information I thought might be of use and is from a paper by Richard E. Kerr, Jr., 1976 entitled WALL OF FIRE -- THE RIFLE AND CIVIL WAR INFANTRY TACTICS.
"The United States War Department conducted a rifle/musket comparison in February, 1860. The results were published in Special Order No. 23, dated 1 February 1860. It was a detailed study of the accuracy, range andrate of fire of the .58 caliber rifle musket against several other weapons, including 1843 Model .69 caliber smoothbores. Figure 3 is a summary of those results for the .58 cal. rifle and the .69 cal. smoothbore fired at a 10 foot square panel. Figure 4 shows a similar test fired at a six foot square panel. The test involved ten men firing 5 shots per category: volley, file and skirmisher. Volley fire refers to firing in line, by fire commands. A file is also from line but without commands; the soldier has freedom to aim and fire at will. The skirmisher category is "open" with the firer determining how, where and when he fires."
(sorry for the same black bars for each weapon, but the rifle musket is the better performing "vertical bar" in the charts in all cases but one I think).
"The charts show that the rifle was effective out to five hundred yards, but the musket lost its effectiveness at less than 200 yards. Also, the data showed that accuracy increased with the freedom given the soldier. In all cases the poorest results were from volley fire and the best, except one event, from skirmish firing. There can be no doubt based on this trial that the rifle had much greater effective range. Hitting a target that is 10 feet by 10 feet only calls for limited marksmanship; it is more a reflection of the weapon's consistency than the firer's aim. This is a good representation of an area target that might be engaged in battle. In fact the rifle did hit between
twenty and forty percent at five hundred yards, where the musket was totally ineffective. Even at one hundred yards the musket could produce eighty percent hits, but the rifle hit almost one hundred percent. When the target was reduced to 6'x 6', less than forty percent of the 10'x 10', the rifle still had the accuracy to hit at five hundred yards. The musket had dropped to less than six percent at three hundred yards. Such a target was about equal to two men standing aside one another. If a unit equipped with rifles chose not to use skirmish fire, but used musketry to fire into a massed unit, it moved the killing zone beyond five hundred yards. The rifle was superior to the musket in every way. The Minie ball gave it equal or better reload times, its range was double or triple that of a musket and it could be expected to hit what it was aimed at -- even at 500 yards."
Just my opinion, but while valid arguments can be made that sometimes commanders didn't give firing commands until considerably closer than the effective range of a rifle musket, or the terrain or environmental conditions might dictate a firefight at closer ranges where a smoothbore using ball or "buck and ball" could perform as effectively or even at greater effectiveness than a rifle musket, does not negate the fact that the rifle musket was a game-changer in our Civil War.