This is a very informative thread, muchly enjoyed.
Compared to these experienced posters, I know little.
FWIW ...
In the dozen or so factory HB Rem's (couple of Savages) that I've tuned, Horn. 155 Amax has proven the least fussy bullet in most of all 'em.
It's long shank does well to reduce jump in SA mag length/deep throated barrels.
The best of them can be made to print consistent 3/8's MOA ... the lessers will stay within 3/4's. Most hover around 1/2 MOA out to 500 or so, MOA'ish to 900 when all is well condition wise.
This with Varget/Lapua/br2's.
If better than that is desired, IMO, a better barrel would be the way to go.