The A1 upper with the 16" barrel you installed fit the lower perfectly! The pins aligned great for a nice tight fit. The rear sight was dead on center and the bolt assembly was flawless.
My wife and I fired 110 rounds through it this past weekend and it fed and extracted with absolutely no problems. She even put 5 rounds in one ragged hole at 50 yards.
Looks like I might have to build another one for myself!