Having been working up loads for 3 new Savage barrels in the past year the biggest thing I found was throughout load developement process was copper. Two of the three barrels coppered up bad for the first 50-100 rounds. Load tests were often scewed by the coppered up barrels.
Every time I "scrubbed" them out accuracy improved almost right away. A good copper solvent and 40 or more strokes with a stiff nylon brush (sometimes twice).
One barrel a 26 inch 10fcp-sr with 5r rifling was pretty decent did not copper up much after break-in.
The 24 inch 10fp-sr is terrible and after 300 rounds still coppers up after 50 rounds or so.
The third barrel is a 22" off an axis and accuracy drops off pretty fast after 40 or so rounds (only has 200 rnds so far).
All three have shot many groups under .5".
But they are hunting rifles and .6 to .75 average is all I expect, even with hand loads.
Mine shoot ok until they copper up. Seems like they are getting better.
Hope you can figure yours out.
Randy