I am also experimenting with modifying some M&P mags and CZ mags to employ during the carbine. You should Minimize the notch inside the front of the mag so it will eventually lock in. I do not have any Glocks. I just paid out $300 for a blue P85 in https://rugerp89forsale14455.canariblogs.com/ruger-sr45-for-sale-an-overview-47204085