Generally this happens from overtightening the receiver screws on wood stock, even laminated wood stock. When the receiver screws are over tightened, this compresses the wood in the stock putting it under a pressure load. When the rifle is fired and over time, this preload will relax from the break down of the wood from the recoil energy. As a result, the torque on the screws will lessen and the recevier in extreme cases can work loose.
Then in most cases the receiver screws are retorques and it starts the process over again.
Even a correctly skim bedded wood stock can do this if the receiver screws are over tightened, the still will still compress.
Only a properly pillar bedded rifle will prevent this from happening.
The round receivers will act as a wedge and will compress the wood more dramatically then a flat bottom receiver, simply point of force issues here. Not only will a round receiver compress more, it will also seperate the wood causing cracks alone the centerline of the stock.
If pillar bedded properly this is not an issue.
Good Shooting!!
Kirby Allen(50)