For clarification: All day long is certainly a misused term. In our case, our .308 will shoot .5 MOA out to 400 yards conditions permitting. The rifle is more than capable, up to the shooter and the wind. If the conditions are good, yes on most occasions we can maintain that. My 14 year old son is a better shot than I am and we both have done around 2" 5 round groups as 400 yards.
We shoot Black Hills 168 or 175g and shoot off a bipod and sand bag. Here is the rifle, range and representative target.