Iver Johnson single shot 20 guage. 3 rounds will bring tears to your eyes and your cheekbone will hurt for a week.
Fired (one time!) a friend's . 308 Norma Mag. Almost dropped the rifle and had a headache for a week.
80 round match with M1 Garand doesn't bother me a bit.
Last edited by jnyork; 07/09/10.