Not to long ago i was coaching the pistol range aboard MCAS New River, and sometime in the afternoon one of my shooters said "hey caoch, how do you keep from flinching when the brass hits you in the face?". I was so used to it that i didn't even realize it was happening! If you're going to be on a range, your going to get tagged with brass, that simple. It's not going to hurt you or bite you, and if you get a little blister from it, i promise it will heal.
Oh yeah, at the end of the day when i took my cover off, 6-7 9mm casings fell off the top and into my lap while i was driving. Scarred me sh-tless.