Maybe a slight adjustment to hold or how you control muzzle jump will help to get your groups centered.
The Krag barrel is so long that there is plenty of room between the action screws, middle and upper band.
It would be easy for a rifle that old to possibly have some shrinking /drying going on that may be working against you to some extent.
Right now, I"m holding left hand on the lower front and holding down on a plastic rifle rest during loading testing. I"m trying my best to hold the same and put the same point onto the rest(just behind rear band/middle sling poing) No rear bag.
I guess once I settle on a load, I should do some offhand shooting onto paper (or even just putting elbow on the table)
What is interesting is that the slower loads are shooting right and the faster loads are shooting left.