Flinching is learned at the range, where you're supposed to use hearing protection, eye protection, and you can even wear a recoil pad like the PAST if you like. In the field I rarely even remember hearing my muzzle blast although I'm sure I do.

People even learn to flinch from shooting a bow...and they can learn to not flinch shooting the very same bow with practice.

If you're shooting next to a person with a brake I also recommend long sleeves because they spit burning propellant to the sides too. They are much louder to shoot next to than behind. My wife weighs all of 130 lb. and she can drill holes like no buddy's business with my .300 Mag. with a MagNaPorted barrel so it's possible to learn good shooting habits even with a brake.

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