I purchased 2 - 300 blackout 16" barrels. I installed them both into uppers and nether one will fully chamber a fully processed case from east coast armory. I have no problem with them in my Givati barrel. I sent an email to where I purchased them and am waiting to hear back. Any thought on solutions???

Need to check them with a name-brand new cartridge, or a gauge.  If the chember was cut to the tighter side of things you can be running into a common problem with a lot of self-loading rifles, the need for small-based sizing dies.  This is very common with the 5.56, and as your reloads are almost certainly former 5.56 cases you can be having the same problem.  If you can find reloads that were initially sized with a small-based die try those to see if it works.  If the new case works and the reloads do not, that's almost certainly your issue.  I do hope that before asking this though you thoroughly cleaned the chamber as machining crud can prevent proper seating of the cartridge in the chamber, but otherwise I'm betting you have an issue with the reload sizing.

Finally, buy from reputable places.  No-name parts from a no-name vender is just asking for trouble.

Try some different ammunition and check headspace...........