Re: 300 Win Reloading???
My Rem 700 XCR Long Range Tactical, with a 26" tube, likes 74.0 grains of H-1000, win brass turned, with a Win Large Rifle primer (all I had during load development), 180 grain Sierra GK, almost touching, shoots 0.5 to 0.75 MOA all day long.
I haven't tried magnum primers, but I just picked up some CCI 250's to see if they tighten up at all.
Another load that worked well was H-4350 and 150 grain Sierra GK, shot pretty good.