My 458 Socom kicks like a 12 gauge , 308's not so much...as mentioned a good brake and adding weight to the rifle should fix you right up.
In my 308 lower assy's, I used VLTOR stocks with the storage on the left and right side...even prior to firing they were so light in weight that I added as many 405gr lead 458 bullets that fit in the tube and topped it off with a foam ear plug for zero rattle before closing each side.
It added a lot of weight to the stock, basically changing it from an ultra lightweight...to weighing about identical to a Magpul PRS stock.
This brake
http://precisionarmament.com/product/m11-muzzle-brake/ was the most effective brake we tried on our actual 308 uppers
http://www.brownells.com/rifle-parts...prod54370.aspx