3 Brownells M16-A1 Barrel Physicals One Barrel had a Chamber Issue and it failed the Front Sight Base Alignment Check. All three Upper Receivers are 1970 era Colt. After the video I swapped around Uppers and got the same results. The Uppers are worn but pass all Alignment Checks. It’s not the Uppers that caused the FSB Alignment failure. Since these Barrels are so hard to find, we decided to repair the bad Barrel instead of returning it to Brownells. We repaired the Chamber Issue with a 5.56 Flex Hone and corrected the FSB by re-aligning the FSB, reaming the holes, and fitting oversized taper pins. We will do a separate video showing the repairs.