First off, every gun is different, so you may find out some thing that works contrary to what I am saying here. I personally feel that the gun should lock up tight with the fore end off or on and the barrel should be a little wobbly with the fore end on and the action opened up. I have a different fore end for each barrel and they have been pillar bedded for each barrel. I can rest the fore end on sand bags and shoot off of them with good results.
Good Luck and Good Shooting