I couldn't like this post twice so I quoted it so I could like my own quote.A couple of additional thoughts. First, for an admitted "newb", you wear a **** ton of kit to the range.
Second, I can rule out any chamber tolerance issues for you if you would like for me to inspect the upper.
Third, this is the second issue I've seen reported this week that involved a Spikes NiB BCG. Second only to the unknown reman ammo you were using, the BCG would be the next most likely cause. Advice: don't waste your time with NiB.
Nibx bcg's are known to cause issues. The coating interferes with the tolerances.
Reman ammo is known to cause issues.