Solid upper for cmmg ar-9 build - Aero Precision AR15 XL Stripped Upper Receiver

Built a CMMG RBD 9 mm upper using one of these last year. I liked it so much I'm building a second one for my wife. It's a tighter fit for the barrel than the CMMG mk4 upper but it works if you use a heat gun on it along with Aeroshell.