I've worked with both a Rem 700 LR and a Browning A-Bolt LR Hunter in the 300 RUM, concentrating primarily on 180-190-200 grain bullets. While I've never tried 8133, I have had truly excellent results with both Retumbo and RL-25 paired with Federal 215 match primers...and if you are looking for some lighter practice and/or barrel break-in loads with more affordable bullets, IMR7828 gives pretty decent accuracy in loads that don't punish the shoulder. My records tell me that (in MY rifles) about 86.5 grains of 7828, a reasonably-priced 180 and any magnum primer gave me acceptable results in the power range of a 300 WinMag. Just be aware that in this combo, the bullet itself will quickly become the limiting factor - if it's not made to run at 3000 FPS from the muzzle, your accuracy will suffer. Therefore, you want to stay away from the cheaper bulk bullets like Rem PSP, though I have to say that the Sierras seem to work fine.
7828 has also worked well for loads with lighter bullets like high-quality mil-spec FMJBT's if you are so inclined, but expect to do a little bit more tweaking to find what works best in your launcher. Again, it gave me reasonable accuracy with loads producing energy in the 300 WinMag range. I have never really spent time experimenting with lighter hunting pills like a 150 but one of my buddies has achieved impressive accuracy with Berger 155 VLD's.
Honestly I'm not a big fan of muzzle brakes...even the heavier rifles will kick with a RUM but to me it's part of the price. I'd rather handle the recoil than the headache from earsplitting muzzle blast...and torturing others at the firing line has never seemed like a good idea.
