Had a muzzle brake on my Armalite AR10 in 308 when I purchased it. It was so loud the gun was unusable without earplugs and muffs over them. I was so glad when President Clintons useless ban was over, so that I could replace it with a flashhider. Unless you are already deaf and or don't need to hear while hunting, I wouldn't reccommend it. I damaged my ears beyond repair the first three shots I took when hunting without ear plugs. I truly think even a deaf person would have a huge headache for days from the pressure.

Agreed, you should not need a break on the 308. You probably won't even notice the recoil when shooting from field positions. Like has already been suggested there are plenty of excellent aftermarket recoil pads like the Limbsaver and the Decelerator. On a 308 imo a break would be a waste of money.