I am also experimenting with modifying some M&P mags and CZ mags to use inside the carbine. You have to Minimize the notch from the entrance in the mag so it can lock in. I don't possess any Glocks. I would use Glock branded Publications and never one other copies. https://ruger-p89-for-sale25566.blogdosaga.com/32024268/top-guidelines-of-ruger-p89-for-sale