Great tutorial Russ, excellent write up and photos! Thank you for posting this and no doubt it will help anyone who's debating whether to build an upper. I hope it does become a sticky as a needed companion to JD's lower build.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek