4" off on point of aim is far too much.You are forgetting that you must add the error in zero to the accuracy of your gun/load combination and then add the aiming error in the field.If your rifle sight in is dead on and your rifle shoots 4" groups at 200 yards and you add 4" or error for shooting under field conditions you will be shooting 8" groups at 200 yards.This will barely keep you in the kill zone but adding 4" more for an incorrect sight in could easily result in a miss or a wounded animal.As far as hitting a 2" target consistantly under field conditions it is really not very difficult for a good shooter with good equipment and a solid rest.I consistantly shoot 1" groups at 200 yards off the bench with my rifles(custom rifles using handloads)and off the bipod or a solid field rest I can consistantly hit a 2" target at 200 yards.Off hand is altogether a different story but many of us stand hunt,use bipods or use any field rest that is handy and do not shoot offhand a great deal while hunting.My own rule for seting my maximum shooting distance is not to shoot at a game animal at any distance I have not practised at on targets.If I had only shot at a 25 yard target I would not even consider shooting at a game animal at 200 yards.