I am also experimenting with modifying some M&P mags and CZ mags to use inside the carbine. You should Reduce the notch during the front with the mag so it will lock in. I don't individual any Glocks. Not lousy, but looking at simply how much factory mags are likely https://ruger-shotguns44444.yomoblog.com/38606447/ruger-sr45-for-sale-an-overview