Any time a spring is stretched or compressed such that its length changes (to the point of deformation) it has been permanently and irreparably damaged. Stretching mag springs can result in improved performance initially, but ultimately it results in a decreased lifespan for the springs. If you believe you have weak springs they need to be replaced, there is no way to fix them by stretching them.I did have a small number of jams that I believe were due to weak mag springs but after stripping the mags and gently stretching the springs I didn't have any problems.
You can replace the springs with new Ruger springs, or if you believe your gun will work better with stronger springs you can purchase them from Wolff at the link below.