If you are talking about the front action screw then it shouldn't matter. If the bedding is good just 'very' tight should be fine. Not so tight the screw driver is ready to fail but quite tight. The rear a bit less tight and, if present, the center screw just tight enough to keep it from backing out.. If your talking about the screw that pierces the forearm and enters a block on the barrel then there is really no set amount. Some even leave them out as part of the free floating process. It is possible to use an inch pound torque wrench but I've not seen it make a big difference. If the rifle is properly bedded, it should make little difference.