Re: 264 win mag 140 gr amax- 300 rum 200 gr sierra game king
Sorry, not H1000. I have reloaded for many rifles in 300 rum and it really likes RE25, 180 Nosler Accubonds, FED215 primers. Try 92 grains and work up. I use 96.0. You must try lower and work up, may not be safe in all rifles etc etc etc.
Also, I have a 264 win mag Sendero. It also likes RE 25 with 120 Nosler Ballistic tips. WLRM primers, 70.0 grains, etc. May not be safe work up from below etc etc etc.
I also used 140 grainers and got good results with H4831, 55 plus grains, work up from below etc etc etc. The 140s did not shoot as well at long range. Need faster twist to really make the heavy match bullets work.