Here is an excerpt from an old book that seems pertinent:
from "A Treatise on the Rifle, Musket, Pistol, and Fowling-Piece"
by N. Bosworth, civil and military engineer
published in New York 1846
"Ball-practice with musket, and guns not rifled.
At the beginning of my practice in sharp-shooting,I had formed an opinion from what I knew, or thought I knew- that a perfect smooth-bored gun, with a perfect ball, would shoot as well as a rifle; and that the superiority of the rifle consisted mainly in the higher degree of finish and attention bestowed upon it.determined, however, to bring the matter to the test of experiment, I ordered a gun to be made with great care; the barrel to be four feet long,of half-once calibre; the gun to be every way finished as a rifle, except that it was to be left a smooth-bored barrel. With this gun, under best possible circumstances of a rest, I made ten shots at a block, forty yards distant, with a medium charge of powder.A circle was then drawn just to inscribe the balls, and from the centre of this circle,each ball being measured, they formed an aggregate of thirty-five inches, or an average of 3 5/10 inches.
Disappointed, and somewhat mortified at the result, I returned immediately to the gun-smith (who enjoyed a hearty laugh at my expense), to have the gun completed as a rifle.
"Stay a couple of hours," said he, "and you can take the gun along with you." The gun was finished, and when he put it into my hands, he said: "Now,I want you to go and shoot in the same place, with the same charge of powder- aiming exactly as you did before; don't mind where the balls go- make ten deliberate shots, and then look at the results."
I did so, and was greatly astonished to find but one hole in the block! The balls had followed each other in nearly the same track, enlarging the hole perhaps a little at each fire, to about an inch across at the greatest diameter. They had, however, glaced into one common centre, each welding itself to those that had gone before, and I cut from the block the ten balls, consolidated into one single mass of lead.
The result was conclusive; the naked undissembled fact, of the superiority of the rifle, stood before me in silent triumph; and I began anew to study the cause of so great a difference in the same gun, where nothing had been added-- where nothing that remained had been changed, and where even a part had been taken away!"
The author took a scientific approach to guns and came up with a lot of interesting conclusions for his day. A very interesting book, if it can be found.
Ben