I've never had that problem with my Sharps, but with my trapdoor, my thumb will sure get me in the nose if I don't get the butt right in the small of my shoulder.
With a trapdoor as you shoot it you start getting sore and don't even realize that you've shifted the butt out onto your bicep. When you do that it'll get you in the face every time, and it's a thump that'll bring tears to your eyes. Maybe that was your problem with the sharps.