Its relatively simple - put some 8" gongs up at various distances, say to 500yds. Then shoot the gongs from simulated hunting positions - try offhand, with a trigger stick, leaning against a tree, etc.... you get the idea!
Shoot at the 8" gongs until you find the range where your abilities will allow you 100% hits - i.e. - hit the gong 3/3 or 5/5 times - Then shoot a deer no farther than the distance you can hit the gongs 100% of the time.
I would bet, like most of us, that you'll find your effective range is well under 400yds, prob closer to 300, for an ethical, clean kill.
I don't think you read my original post....I wasn't asking what my effective range was (my effective range will vary with the shooting circumstances around the shot), I was asking what people feel the effective range of the 308 win was.
and BTW, my effective range offhand is no more than 100 yards