Wow, well ... that assertion is not only wrong, and defines physics, but is total BS ...
EVERY barrel maker and/or firearm maker using such barrels bends their barrels .... muzzleloader barrels or not. Every custom maker of MZL barrels (I have a list of 8 names ... you?) bends their barrels. Bobby Hoyt may have to bend every barrel send to him; as in fact he just told me a few weeks ago that that the 1st thing that he does to EVERY barrel sent to him for work, before he works on it, it so check it for straightness and to bend it straight if needed.
Many of us are using any and all of the barrels as listed , so if there were an issue or this alleged 'hook' anomaly ... well we sure would have have heard about it and have been worried about it before now!
I've bent many a barrel, MZLs or modern, smoothbore or rifle. Now take my fully tapered round 75-cal custom 60" long smoothbore barrel (no rear sight) by Greg Christian. She was off @ 50-yards, shooting way low, and you can't file down a low front sight that is already very low, and there's no rear sight to adjust, so I bent the barrel. One cannot visually see the bend in this particular barrel, but the good bend is clearly there; I know, I bent it myself, with witnessed too. Now she's a tad low @ 25, dead nuts ON @ 50 and @ 100-yards, well there I really need to 'show more barrel' or hold high(er) on the targets. No left or right variation induced. And yet wth your alleged 'hook' hypothesis, she should have continued to climb well up and off the target high! But not so ...
In fact, NONE of the many barrels I've bent for me or others display any hook at all. Me thinks you've never actually bent a barrel on purpose, because if you have studied or are knowledgeable on exterior ballistics, it's impossible to induce such an effect. May I suggest you start with Dr. Mann and if you need to look that name up ... well then it's clear you have an opinion that has the 'hook' and defies scientific fact, LOL!
In exterior ballistics, i.e., once it has left the muzzle, for the projectile itself there is only yaw, pitch and roll (or spin), where a change in any of those 3 factors requires an external/other force to induce the change. Please re-read up on Newton's 1st Law of Physics. So please tell us ... what is that phantom force that none of us are aware of? Known external forces are of course, gravity and drag, where the gravitational force always acts vertically downward on the bullet, regardless of the bullet’s orientation relative to the vertical direction, and where aerodynamic drag always acts opposite to the bullet’s direction of travel through the air.
Other factors influencing the projectile's flight are the wind, i.e., causing drag, shooting up or down hill, the temperature of the propellent as it affects the combustion, affecting the velocity and perhaps the Coriolis Effect (spinning of the Earth) if shooting a far, far long distance away. Most small arms Ballistic Tables are factored on 4 of the 6 'degrees of freedom' of the trajectory analysis, lumping the effects of pitch, yaw and roll/spin into the effect of a yaw-of-repose to account for the trajectory. But note in the interest of science and full disclosure, that in long distance artillery shooting (i.e., shooting 20-miles away or more!), they factor in all 6 DoFs as a separate variable.
You spent a lot of time to ignore physics. F. W. Mann never published a test with a smoothbore rifle but did discover things we call "yaw precession" which, according your reference to Newton's laws, couldn't exist either. It would be a good service to attend your local driving range and inform all those there who are working to control their slice that they are wasting their time trying to correct something which does not exist.
Now, if you will discuss only the facts relevant to a BARE ball in a hooked, smoothbore barrel, then perhaps we can have an intelligent discussion, but I seriously doubt that because your mind is made up and you seem so hellbent to make me out a fool. I don't really care what you think, or about your many paragraphs of irrelevant, red herring evidence, but only about what actually happens when a round ball develops a spin from the side of a hooked barrel and the resulting aerodynamic forces cause the ball to travel downrange in an ever-increasing arc. Perhaps it is relevant to mention that the smoothbore that exhibited this phenomena for me had a bend in the last three inches of the barrel, and it went away when I straightened it.