I just developed the following 300 RUM load:
230-grain Berger Hybrid OTM bullet
COAL is 0.003" off the lands
97.1 grains of LRT powder
Norma brass (new, no prep)
Federal 215M primers
Results: 0.192" three-shot 100-yard group, 2,956 fps muzzle velocity
Neat powder; tiny spherical kernels will let you meter extremely precise charge weights (+/- 0.02 grains), if your scale can manage it.
This is also a good powder for the 300 PRC with heavy bullets. This is a 5 round string at 620 yards, 87.5 grains pushing 225 ELDs yielded 2932 fps. I plan on trying it with the 245 burgers soon.
SD 9 ES 19What kind of ES/SD were you getting with that load? What brass and barrel length?