I'm also experimenting with modifying some M&P mags and CZ mags to make use of while in the carbine. You should cut the notch within the front of the mag so it'll lock in. I do not own any Glocks. oil on everyhting else. When I delivered mine to Ruger https://ruger-p89-for-sale12222.azzablog.com/32248448/ruger-shotguns-an-overview