Man Bigtimer, I feel for you. Evidentially you've never read Semisane Ten Laws.

On a serious note, it sure sounds like a scope problem. With the groups you were getting with that load I just don't see how you could be getting such wide variance now with a 12+" group. Temperature and loading technique differences may account for an inch or two, or three - but nothing like that. Got to be either a sight problem or serious damage to the muzzle.