I'm curently building a .300 RUM on a blue printed REM 700, 30" Shilen SM barrel and I'm wondering about what powder to use. I'm planning on shooting the 210 gr Berger hunting VLD. I've used H1000 in my .338 Lapua with great results but have had alot of people say that the Ultra mags do not like it. RL25 seems to ne a favorite, but where I live in Utah the temps go to the extreme. What are most of you using?