Well the bolt lockup in the barrel will control that PSI but the action isn't the smoothest even made of the material it is made of. I understand they are now offering "Metal" recievers for 2005.
Even though the bolt locks into the barrel the chamber is still expanding and causing the receiver ring to expand and contract with it each time the gin is fired. I know that it is pressed in with a good ammount pressure but press fit things tend to wallow out over time with continued movement.
The receiver is not applying pressure in a linear direction like on a threaded barrel but rather in a "crushing" fashon and is only relying on friction to hold it in place.