I just sold a Ruger 10/22 magnum about a month or so ago. I've had it for a good while, and ran probably 7000-8000 rounds of mostly hyper velocity, and heavy(50g) loads through it.
I mounted a Leupold 6x36 on it when I bought it new(in the Ruger rings), and it never gave me a single problem. I also know a few other local guys around me that have 10/22 magnums, and none of them have had any such problems either that I know of.