Anyone tried this powder with 200-220gr Matchking bullets ? How did it do ? Any starting or max loads ? So far RL25 has worked the best for me with the 220gr bullets. Just wanting to try something new.

Tracer,

Welcome to the forum.

We have tried H5010 in our own 30/404, which is very close to the 300 RUM, with 240 MK.

100 grains - 3100 fps - 0.268" for 5 shots
101.5 - 3164 - 0.438

I hope this helps.

With 200's, H-50BMG From 97.0 grains to 98.0 grains and Remington 9-1/2 primer.

My preferred load uses AA-8700 and Remington 9-1/2 primer.