That’s true. If I didn’t screw this up, The math works like this, the fastest that a human can react to something is 100 milliseconds (.001). A bullet travelling at 2000 fps leaves a 28” barrel in 80 milliseconds (.0008) .0002 seconds BEFORE the shooter can react to the recoil. If it was the physical recoil that prompts a flinch, it would have no affect on accuracy since the bullet is clear of the barrel before the flinch. Therefore, for a flinch to affect accuracy it would have to happen BEFORE the shooter actually feels he recoil, hence the flinch is a mental affliction caused by the anticipation of the recoil. Like you said “ math and physics don’t care”. Of course a shorter barrel or faster bullet is clear of the barrel with more time to spare before felt recoil