You might not be interested in Ruger factory mags for the -14, but Ruger began selling larger types (20-rounders) to US civilians just after the last presidential election.
Last spring, they began selling 20-rounders for the Mini 30.
Owners don't always like the price, but claim that they are much better than most aftermarket higher-cap. mags.
Much more at "Perfectunion", "Mini 14/30", "Magazines".