I experienced more borderline flinching with 338 and 375 H&H, 416 R rifles.
In New Mexico, I obtained a rifle that I thought would cure everything, including
a slight anticipation of recoil: An 1874 Sharps chambered in .50 cal (50 3 1/4).
A 725 gr cast bullet.
Went back to 45-70 Sharps and 3 in shotguns for shoulder relief. (No flinching with shotguns.)