I have done some testing on harmonics of a barrel by taking a 20" 10-22 barrel and chopping 1/2 inch at a time and shooting for groups
with the same ammo at each length.
Started out with 1.25 groups and it got better after I took the first inch off then the groups grew again and after a few more chopps
the groups got small again.
Done the same test with AR dedicated 22 barrels, 223, 308 and even a couple pistol caliber barrels and they all did the same thing.
You could call it finding the wave for your bullet to ride on.
This is one of the reasons hand loaded ammo can get some of the best groups possible from a barrel as
you they can make a load that rides the smooth part of the wave, with 22 Lr you just need to find what ammo the barrel likes
or start chopping the barrel to work with the ammo.
For most its easier to find the ammo that the barrel likes