You have to loctite it. Or go with Jack Weignd mount.
I think he saying the screw is tight the Mount is Loose am I correct ?
I have no answer but I would Go real fast to the Ruger Forum and ask those Guys also on here is axehandle
look him up he has a lot or six guns
You need help fast Go to PM's with anyone you see on here that seems to have or Know about Pistols
I'm sure no-one would mind the PM
Good luck hope its a Simple fix
Tommyt