I'm also experimenting with modifying some M&P mags and CZ mags to work with during the carbine. You need to Lower the notch from the front with the mag so it'll lock in. I do not have any Glocks. You'd probably never ever have the capacity to notify the gun https://franciscouziee.blogdigy.com/5-easy-facts-about-ruger-shotguns-described-48008050