Bigtim,
I'm prolly the last person on here you should listen to about correct loads and charges with a ML, but I thought I'd chime in to tell you that my Omega was throwing up those same wild ass groups when I was packing it with too much powder.
My background as a hunter is in archery, centerfire, and shotguns where magnum loads and high velocities are - at least a lot of the time - good things. So when I got a ML I started read through the ballistics guides and I saw that the magnum charge is 120 - 150 grains, so naturally I thought that I what I needed to be using. I got on here and found out that I was WRONG. So now I have a new container of Blackhorn 209 to try out so that I can determine the precise charge that works best out of my Omega.
I just wanted to tell you that since it kind of sounds like you may packing your loads a little on the hot side and getting some unsatisfactory results like I was.
Hope it all works out bud.