Originally Posted by digits
Moa? Yes no ?
Really depends on teh optic and realistic range you plan on shooting, along with your chosen load. If you need an extra 20 MOA of elevation to get the round there, then yes.
20 MOA at 1000 yds is 200 inches. If you have to make up for 200 inches of drop. then you need it. Beyond 1,000 yards the .308 isn't going to be the besat tool in the box for a "tactical" application. Mostly the 20 MOA risers are for true long range calibers like .300 Win Mag, .338 Lapua, 50 BMG, etc that have reach beyond a scope's adjustment range. If you are looking at taking 1 mile shots you should look at another caliber first.