I've reloaded and shot the Hornet fo 40+years. Much data....
I actually partially full length size my Hornet. My Ruger M77 has an out of round chamber that is not exactly axial to the bore. It shoots MUCH better if the cases "lay" in the chamber the same way round to round.
Best powder varies with bullet weight. 33-35, H110/296 is best with #2400 getting honorable mention.
40-45gr, it's Lil 'Gun. 12.5gr with a Sierra Varminter hollow point (or Nosler Varmageddon) at 1.780" is the best load, at nearly 3,000fps.
50gr bullets (heaviest that are accurate) over Acc1680 has given some amazing groups, though is a tad slow. 2500fps, but once got a 5-shot one-hole group. Exact 5 same cases, powder charge, bullets, next day did not duplicate results, but was still 3/4" at 100yds. Actually, rare for my rifle. 1.5-2moa more typical.
I just this week I took the Hornet out and shot up all my mixed lot cast bullets.
So long SR4759!!! I shot some sub 2moa groups with both the Lyman 22541 mold (old before now called 225415) and much more recently Lee .225 55gr RFGC. 7.0gr SR4759 is fabulous in the Hornet with cast bullets.
Other good powders are Unique (of course!), at 4.6gr, and #2400 at 6.2gr.
So far, with the .218 Bee I recently aquired, nothing beats 7.4gr. 1,850fps and 2moa. (With cast).
Fortunately, 8oz of powder goes a long way at 7gr per charge...