So, .750" average at 200. ... .375 moa. Mostly vert. She's shure 'nuff a shooter you got there minniehill. I'm thinking, what you're really wanting is 1/4 moa and those oval bugholes?.
The first thing I look to, when vert. gets to be more than horiz., is how the rifle is recoiling. For example, a rear sling swivel hanging up on the bag, or the toe touching ground, can throw shots high/low.
If that ^ isn't whats causing the vert. in your groups; then once you have achieved "no stress" perfect bedding, and, you have no run-out in your loads, 'match grade' .... then it's now down to(maybe)a bullet swap, and then some some load/seating depth tweaking to reach your barrel's absolute potential.
Sorry for sounding like a broken record here Mate, .... and I'm probably boring you silly, but, you've got the only Creedmore I've ever known of, and I'm so curious as to how good you can make it shoot.
The offer stands: if you want to try some 139 Scenars, and/or 140 Amax ... I'll drop 'em off to ya.