New pm237b quick change 9mm mag block - Pro Mag AR-15 / M16 9MM Magazine Adapter Block For Colt 9mm SMG Magazines, Quick Change

I bought this because I wanted to see how it fit and if it was really quick change how it says. I ordered it from Optics Planet on backorder not really caring when I got it. Arrived about 8 days later as advertised. On first opening the package it looked good (mostly polymer design) and came with straightforward directions. I immediately took to it using my Anderson lower. It inserts in 2 pieces from the bottom with the ejector side installed first. It's a tight fit and it needs to be finessed to make sure what appears as a LRBHO metal slide goes underneath the standard bolt catch. Yes make sure that piece is under the bolt catch. When installed properly the block will snap in place and be locked in by the magazine catch. Next from the bottom from receiver the fred ramp slides in and will lock into the magblock. This thing fits perfectly. I did try fits w dummy rounds in a plastic ASC mag and a metal C Products mag and the both locked in. The cheaper plastic mag seemed to take better but both worked. I will report back after taking it to the range with different mags. So far the fit is perfect with it being mostly polymer so long term I don't know? When installing and the feed ramp doesn't slide up freely and you find yourself really forcing it in... That means you don't have the first part of the block in properly! Final thoughts so far is that it installs completely from the bottom w no alteration to your completed lower and it comes out with the press of the button on feed ramp and magazine release.