Reposting from Troubleshooting as someone suggested I post under Faxon's page...
Hi!
Just finished my first AR build. Brought it out to test fire, noticed the casings had a waxy look on them after ejecting, looked like the ejector chewed on 'em a bit, & when viewing a video of the first shot I saw a fair amount of gas exiting the chamber. Only shot 5 rounds in total as I hadn't tested headspace & figured it wasn't worth blowing my face off. In the middle of the 5 rounds I swapped out my new BCG for my Colt's BCG (~2k rounds) to see if that would change anything, seemed the same. The hole on my gas block (BCM) seemed generous in diameter compared to the hole in my barrel, so I'm fairly confident that my gas block is aligned properly. The rifle cycled fine, locking back on an empty mag (only loaded a round or two at a time). I asked a gunsmith behind the counter at the range I was at to take a look at the casings. He said it looks like I have a rough chamber (new barrel). He wasn't very friendly & didn't seem to want to talk to me, otherwise I would have seen if I could have paid for him to check it out.
New account character restriction cutting me off, see part 2 below...