So I bought a bunch of the Mec-Gar 15 round mags for my P228 after the ban ended. I also ordered spare springs and followers (these followers). On a whim I stuck one of these new 15 round followers in an older P228 13 round magazine and it worked just fine... now with 15 rounds. Putting a new 8$ follower in an old 13 round German Factory Sig mag makes a very nice 15 round range mag. I'm not comfortable enough with this "upgrade" to carry the old mags, but that's what I'm using the new mags for!