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It seems that the issue of rotation and stability has more to do with firearms with long range. The stalking skills of the hunter in closing range with big game have more importance than ballistics for muzzleloaders. A smooth boreshot gun with buck shot will do the job, but does not have the tradition and feel of a smoke pole. Am I thinking correctly, here?

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Welcome to the forum. Rules are to join in and have fun. Other rules are in the board stickies.

I moved your post to a new thread since it wasn't quite on topic where you put it.

I've seen bullets tumble at short range and keyhole targets. How far forward of the muzzle tumbling starts depends mainly on the length of the bullet, which is the lever arm by which air resistance turns it end over end, and the rate of spin. Faster spinning is harder to overturn.

In the case of a round ball, there are no direct overturning forces from air resistance if the ball is a perfect sphere, like a ball bearing. However, there are forces that can cause a ball to roll forward in what would be end-over-end if the sphere had ends, and this has a rotation component perpendicular to the axis of the bore. Examples of these forces would include uneven muzzle blast against the ball due to crown or patch asymmetry, uneven bore friction or uneven gas bypass inside the bore when no patch is used. This off-bore axis rotation causes forward air speed to be different over the surface of the ball on opposite sides. That makes the ball hook in flight due to Bernoulli's principle, same as a curveball does. The exact amount and axis of that off-bore-axis rotation determines how much hooking happens and in what direction it happens. This tends not to match very exactly from one shot to the next.

Spinning a ball in rifling makes it more accurate by the gyroscopic effect preventing any rotation other than coaxial with the bore axis at the muzzle, thus preventing any uneven forward air flow over the sides. Hooking is thus prevented.

The bottom line is that you need more spin as bullet shapes get longer. Most muzzle loader bullet shapes are stubby compared to modern bullet shapes, so they need less spin for best accuracy. It does take distance for tumbling to cause a projectile to hook off in one direction or the other, so on large targets at close range, even unstable bullets will still be effective, which is what I think you were referring to.

If you want to try an experiment, shoot a group from a musket with round balls. Then get some less brass and aluminum rod turned to the same diameter of your round balls, and cut into lengths that give them the same weight as the round balls. Then shoot groups with them. You'll find the biggest groups are with the longest (the aluminum) projectiles because they overturn and spin off more quickly. The brass will be inbetween.

So, bottom line, your thinking is correct that when a gun has no rifling (nor rifled slugs) then you'll need to get closer to the target to be sure of hitting it.
 
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