I'm also experimenting with modifying some M&P mags and CZ mags to make use of while in the carbine. You have to Lower the notch inside the front in the mag so it is going to lock in. I don't possess any Glocks. When you purchase by way of hyperlinks https://archerdfcax.topbloghub.com/38507252/a-simple-key-for-ruger-p89-for-sale-unveiled