a control group with the 55's?
Your groups looked exactly like mine with same bullet/powder combo. Higher the charge bigger the group.
I ended up taking a gamble on deeper seating .010 at a time with 38.5 grain load and at .050 off they all go in one hole all the sudden.
Don't be too locked on being so close to the lands just because the gun has shot most bullets best there.
I found best accuracy at the 2950fps average.
PS same could work and be true with the 42.5 charge was well, as 3200ish should be close to the next higher node.
It might pay to try varget with Sierra 85 gr. HPBT.
I can tell you from experience a 95 partition, 100 grain horn or sierra and 42 ( or so) I4350 at 2900 (or so) deadly on mule deer, coues and antelope. since re26 is temp stable and decoppering AND you can get 3211 from a 100 grainer I would try it . alliant will send you their phamplet free. and it is one line. I shot it out my 7mm mag I got small groups and 86 fps over their manual.