Reloder 22 and 25, H4831 and 1000, IMR 7828 and IMR 4831, Vihtavuori N165 and 170, Accurate 3100. Plenty of suitable powders for the 300 Win Mag.
In a 24" barrel, you should get 3100 with the 180's and right around 3000 with 200's.
I shoot the 308 Norma Mag a lot, and there is next to no ballistic difference between it and the 300 Win Mag.
My pet load with the 180 Scirocco in my Custom M700 is 7x.x grains of IMR 7828 for 3140 fps, and sub moa consistently.
Another 308 Norma rifle prefers the 200, and I am using a stiff load of RL25 in it for 3030 fps...similar accuracy to the above.
Dave.