Hey guys, I need to lap the receiver extension, it is a little to long. From what I've read Aero's are known for this. I am mating a Faxon barrel to it with a Fortis Switch hand guard. When I put it all together there is a gap between the Fortis and the Aero upper about 1/8", also the barrel pin is about 1/16" from fully seating in the extension. The barrel extension does not reach the feed ramps also, there is a small step from the receiver ramps to the barrel ramps, looks to be about the 1/8" I need. Thanks