Barrel harmonics are a consideration when you reference the sight line in relation to the point of aim, it isn't an issue if you are only considering where the bore line is pointed.
Harmonics change the location of the muzzle in relation to the sight line not the location of the muzzle to the bullet's trajectory, that trajectory is still the same it just begins a little higher or lower according to the vertical component of the harmonics theory. Note - barrel harmonics actually cause barrel to move in all directions. The muzzle moves in a circular motion, the muzzle moves backward and forward as the barrel shortens and lengthens, and the diameter of the bore reduces and increases. But the harmonic theorists usually only consider the vertical motion since they believe that their theory will have the greatest effect on that direction of motion.
Harmonics change the location of the muzzle in relation to the sight line not the location of the muzzle to the bullet's trajectory, that trajectory is still the same it just begins a little higher or lower according to the vertical component of the harmonics theory. Note - barrel harmonics actually cause barrel to move in all directions. The muzzle moves in a circular motion, the muzzle moves backward and forward as the barrel shortens and lengthens, and the diameter of the bore reduces and increases. But the harmonic theorists usually only consider the vertical motion since they believe that their theory will have the greatest effect on that direction of motion.