I have a single 360 Nitro which with my first cautious loads shot high and left. As I approached the original velocity with the 300 grain bullets the groups came down and right and tightened up. When I give her the last 100-150 fps I fully anticipate the shots will be right on the sights and as tight as they will get.
This makes me wonder if you are right handed or left handed? And the same for CJF, right or left?
In my one experience with regulating a double rifle, I did have a right-left issue. Just worked on convergence (which does involve right and left, but not together for both barrels, of course).