Follow up review - Aero Precision EPC-9 16in 9mm Threaded Complete Upper Receiver with Flash Hider

Following up to the last review i wrote. Found out why I had the failures to feed. I have a 5.5 inch barrel so since it is under 7.5 inches. The buffer spring should be for standard carbine spring and not the 308 spring. Not the 7 oz buffer either. I used a 5.4 oz buffer and carbine spring with a spacer. Ran 500 rounds NO issues.