There's not really any reason to not have one, unless you want a suppressor instead. The .308 doesn't have a lot of recoil in a heavy precision rifle anyway and .308 doesn't have a lot of gas volume to work on the suppressor, but there will still be positive effects. It will definitely reduce recoil.
If you are getting muzzle flip or bouncing off target during recoil from the prone position, with a rifle over 14#, you have a problem with rifle ergonomics, fit, or your shooting position. I can spot hits with my .308, .260, 7mm RM, .338LM, and .50BMG.
There is a wide variation in effectiveness between muzzle brakes on the market. Some have marginal benefits and some work very well.
I recommend the Badger FTE brake.
Last edited by Zak Smith; 09-01-2010 at 14:05..