Welcome aboard, Tim. My first thought was also scope/sights, don't forget to check stock screws as well. If all seems snug, I'd look at the breech seal, lots of the Shadow variants can be tough on them. Have you noticed any difference in the way it feels or sounds when you cock it? If so, that might indicate a spring problem. One other possibility, check your muzzle brake. Another forum member was mentioning a possible clipping problem with one of his guns, and another friend of mine had the brake come completely off his S1K. Hope this helps, and keep us posted.
Dave