A few points:
Minié ball, not "Minnie". Minié was French.
This seems basically correct. The key point is range estimation, and while you actually can train everyone (an essentially random grab-bag of British battalions at Inkerman achieve a hit rate 10 times better than Civil War combat at Inkerman, a battle which includes periods of fog and long range firing; about a third of the British Army were able to shoot out to ranges of 900 yards with effect on the range) you need to actually do this training.
I think there was a general misconception during this period that rifles were more accurate, and that therefore having a rifle made a soldier more accurate. In fact if anything the switchover to the (US-style) rifle-musket was if anything a downgrade for the average soldier, because it was slower to load (very tight windage) and made them no better at shooting.
The British Enfield with British ammunition and a British-trained shooter would achieve increased accuracy with little loss of rate of fire, and is a very different beast.
Thanks for the correction.
In my defense I'll just say I went to public school.
The next time I need to name that particular type of bullet, I should use the term "Burton Bullet" after the Assistant Master Armorer at Harpers Ferry who made some modifications to the Minie' ball and it was Burton's modified bullet that was used by the U.S. Military. But Minie' got the better press so his name stuck for hollow-based bullets.
I agree that the U.S. troops were as trainable as any troops in Europe. But when comparing the American army, largely made up by volunteers and lead by volunteer officers (at least in the lower grades), against any professional European army, to me only shows what could be possible if the American War Department placed some value on better training. One reason the War Department was against arming the troops with repeating weapons was that they felt that in battle, the soldiers would waste ammo by firing too fast. If the War Department felt that way, then I can only assume they must have felt that it was a waste of ammo and money to train the soldiers to be more proficient with their weapons.
I don't think there was no misconception that rifles were more accurate than smoothbores; they were more accurate then, as they still are now. The armies of Europe had proven that a rifled weapon was the future of warfare, and America was trying to catch up by converting their smoothbores to rifles. Whereas Europe had professional standing armies because they tended to fight with their neighbors quite often, America had a huge continent that was still unsettled so there was room to expand, and two oceans to protect us, so we relied on a small professional army and a volunteer militia system that could be called up if and when needed. What America lacked was the training. H. Berdan founded the USSS and they showed what was possible in long range shooting. But Berdan and the military didn't train these men in how to shoot. They already had those skills when the entered the service. The Army provided the tools; they provided the skill. In the right hands, the rifle musket with the Burton bullet was superior to a smooth bore weapon shooting buck and ball in all cases except at close quarters. At distances at 100 yards or less, using a buck and ball load, the smoothbore puts more projectiles downrange per shot. The rifled musket was designed for longer range shooting, but it wasn't used for what it was designed for because the military didn't train the troops for this type of warfare. The rate of fire between the two weapons was essentially the same until the fouling began to build up in the rifle. In the mid 19th century, the British was the premier military organization. Along with better training, their equipment was first class. Perhaps their Pritchard bullet design was better to keep fouling to a minimum, but the English powder set the standard for the world. Black powder fouling, as long as it stays moist, doesn't hinder loading. One reason the bullets carried lube on them is to keep the fouling moist/soft. The Pritchard bullet with its greased paper patching along with the superior powder appeared to be the better combination than what the American army had.
As some may feel that this thread has drifted off topic I'll conclude my post with this antidote. When I first joined the N-SSA, I had the opportunity to fire both a reproduction P53 Enfield and an 1861 Springfield so I could decide which musket I was going to buy. After shooting both, I settled on the Enfield. The Enfield has a straighter stock than the Springfield, meaning the Springfield has more drop to its stock. Upon shooting, I felt the Enfield, with its straighter stock gave less recoil to me than the Springfield, which had more barrel rise upon firing than the Enfield. The amount of recoil was the practically the same for both weapons, but I felt more recoil effect with the Springfield. I'm not a small person, I am 6'5" and at the time weighed 230 pounds. The average height of a U.S. male in the 1860's was probably around 5'8" and weighed maybe 130-140 pounds. The effect of recoil on a smaller person who weighs 100 pounds less than me should be affected by the recoil more as my body weight offers more resistance to the recoil. With the barrel rise upon recoil, a smaller person may be advise to "aim low."