What is the best bullet/powder combo for the 300 Winchester in the 28 inch Proof Research barrel?

I’ve had great luck with the 212gr ELDXs and H1000 as well. Haven’t been able to find H1000 in stock anywhere near me lately though. Powder availability can be a limiting factor with how much powder the 300s burn through.
 
I made a bonehead decision back in December. My local Scheels had 5lbs of h1000 on the shelf when I was there. Thinking there’s no way it would sell out before I got back I left because I didn’t want to carry it through the mall all day. When I got back it was gone and I haven’t seen any since.
 
ive now loaded for 5 different 300 win mags that shoot under 1 MOA with this load:

180 nosler ballistic tip or 180 accubond
75.5 reloader 22
stay at SAMMI C.O.A.L
CCI 250 primer
Winchester brass

If you don't find desireable accuracy with this load I'm sure you could find something acceptable from 74.0-76.0 grains of reloader 22 w/these bullets.

Obviously work up to this load if you decide to use it, it is right at maximum in the books.