I have had the same problem.
One way to get rid of a flinch.
Is to get a 22 revolver.
And stager the ammo with fired empty cases.
But don't look to see where they are in the cylinder.
Then shoot at a target.
The empty cases will act like dmuuy rounds and after a while you will slowly get rid of the flinch.
And when you snap on the live rounds it will be unexpected and
You will over come the flinch.
I hope this helps.