I have had my SW22 apart at least 50 times and never have had any problems with the screw that holds the barrel coming loose. The take down screw tightens just as expected and has never come loose at the range.
Take down effort is always the same.
If either screw is coming loose during a session, it is best to contact S&W to get it serviced.
It is my belief that the threads are such that when the correct torque is used, the screw stays put.
I have never used loctite or a lock washer as some have suggested.
Also remember that the take town and barrel screws are different sizes.
And I cant understand how undercover could get the frame apart with the take down screw still screwed in the barrel.