If you're considering just a 7mm Remington Mag, I would not bother with a muzzlebrake. The advantages of a muzzlebrake only outweigh the disadvantages with the really hard kicking cartridges, or in the case of varmint rifles to control muzzle jump so the shooter can spot his own shots. The 7mm Rem Mag kicks only slightly harder than a .30-06, which is stiff but not unmanageable. Like mentioned above, the muzzlebrake will make the rifle extremely loud, so loud in fact that it WILL cause permanent hearing damage is shot without hearing protection. If you put a muzzlebrake on it, you will need to wear ear plugs even in the woods if you value your hearing. It will also not make you many friends on the range. I believe you'd be better served by investing in a top end recoil pad (i.e. Limbsaver or Pachmayer Decelerator). Also, don't buy the lightest weight rifle you can find. Lighter rifle=morre recoil.

If you absolutely must have a muzzlebrake, I'd suggest you look at the Browning BOSS equipped rifles. They come with the ported BOSS muzzlebrake and a non-ported extension (called the BOSS CR for Conventional Recoil) so the rifle can shoot to the same POI as with the brake, without the extra noise, for field use. Savage also makes a muzzlebrake that can be twisted to close the ports (noted in the Savage model number with the suffix "AK").

Mike