Ive had the same problem. Here is a few ways to overcome this

1. have someone put a certain amount of bullets in the gun then shoot them all and on the last shot see how bad you flinch. Since you dont know how many is in the gun you will prepare for a kick so you might see a darastic flinch.

2. shoot for a while doing a slow squeeze of the trigger. in that case you dont know when the gun will fire so you cant flintch.

you might want to get that scope checked to see if the eye relief is ok. It might be the scopes problem.

Work on those 2 and youll quite the flintching. I gauarantee it!