I've been bringing in the Double Diamond LE 9MM lowers for customers for the past year. I was convinced that for 9MM AR Builds this is the lower. There is no Mag Block necessary and the Magwell area is milled to accept the 9MM magazine. The DDLE 9MM lowers use Colt Magazines and there is a new version on the Horizon that will accept the Glock 9MM and 40 S&W Magazines.
Double Diamond 9MM AR15 Lower Receiver with Parts Kit