I think I'd have to give Ruger a call. Myself, provided I had one for the pistol and a spare in case it quit working, wouldn't worry too much. My Glock 19 comes with 15 round mags, one I use in the pistol for maximum concealability, I carry Glock 17 magazine for a reload. The 17 round spare magazine hides as easily as the 15 round. You might consider using 17 round SR-9 magazines the same way.....