Talked to Brian today and got the answer. It's an Armor Alloy barrel. T/C plated those barrels inside and out. So, when SSK cut the chamber, it peeled/was rough in a small amount where the plating was removed during the reaming. Brian said that's unusual, but can happen. That kept my rounds from chambering fully. He is going to polish the throat to smooth that transition area down a bit. Hopefully I'll have it next week and can get to load development done. Thanks!