Probably yes. Where does it hurt? How badly does it hurt? How long does it take to return to normal? What shells are you shooting? In my experience, 1 oz loads can cause soreness (not pain) in the the pocket of my shoulder, but I have a lot of arthritis in my shoulders. Heavy loads can cause pain in my shoulder and neck--including my support side shoulder. My advice is to check your mount and gun fit, and be sure to shoot a reliable, reasonable load. One-hundred rounds of target load should not be causing pain, IMHO.