Originally Posted by ralfus
I have a rifle that shot .4"-.5" that went to 1.5"-2" after not being shot for a few months. Drove me nuts until I remembered replacing the action screws with allen heads just before putting it away. The new front screw was touching the bolt's locking lug just slightly. Worth checking out. Sometimes the little things get overlooked. Now that was on a Win 70 but maybe your front screw might be bottoming out on the receiver with an imperceptible amount of movement.
This happens more than folks realize. Especially when the receiver's bedded against plain wood. Not so bad with flat bottom recievers (Win. 70) but round ones sometimes split the stock between the magazine cutout and recoil lug (any round receiver).
Decades ago before epoxy bedding came about, smart competitive shooters would loosen their stock screws after a day's shooting. Then torque 'em up to the desired amount when back at the shooting place. I've known a few varmint hunters who did this but few other do it at all.