I've had good luck with the Mueller scopes as well..One thing you will want to consider in the higher power scopes is the potential for mirage on hot days at the higher powers.
Generally, once you get over 18x, mirage becomes a factor and precision shooting is more difficult. But the extra magnification is nice when it's not present.
Shooting over Prairie Dog towns where the target are small and the distance can be longer, I've had better luck, as far as mirage is concerned, with my scopes in the 4-16x range, set at 16x..
I have two 8-32x scopes and on a .223, elevation availability is a consideration at 600 yards, I'm not sure what elevation factor is involved in a .308, but you should check your trajectory charts on it prior to buying your scope and insure that the scope can meet the requirements..you may need to get a special riser in order to meet them...