I recently completed another upper build and decided to film it as a tutorial for those who haven’t built an upper before. This is my 7th or 8th upper build now (forget exactly how many). I do not claim to be an expert but have learned a few things along the way. Hopefully it is a help to some. I should have some more vids coming soon. Enjoy.
http://www.youtube.com/user/R0GUEKN1GHT#p/u/4/ZVwqhYQInvY
Check with the manufacturer of that gas block, some of them are designed to stand off the shoulder of the barrel a little bit to account for the presence of a handguard cap. If you aren’t going to use something like roksett or pin that block in place, you may want to make sure the first set screw is centered in the dimple and stake it in place. Centering the set screw may pull the gas block forward off the shoulder.