OH MAN I was shooting with a friend I will not mention his name but he thought that adjustment knob was for focus.
He mentioned how well his ammo shoot the week before but could not shoot 2" group today.
I fixed it for him and his focus ring was cranked down so tight it took both of us to break it loose.
His groups punched a ragged large hole after I set it up.
he was shooting 6PPC !
I was amazed to see a 3-9 scope with Parallax setting for sale here on the forum and had been asking myself why are the low power scopes not available with that adjustment.
I do the same thing he does in the above video move my head slightly left,right up and down and set my parallax.
One more reason to have the same hold and same cheek weld and eye position.