form a materials stand-point, so long as the spring never got hot it should be fine. simple man's rule is, if you heat a spring up hotter than you can stand to touch with a bare hand, you've messed up the temper and the spring will lose memory. get it too hot and it's gonna get brittle. if it discolored, it's gonna be brittle.
someone who knows 1911 mags better than i will have to pipe up about modifying internals.