Also you may know that some of these Tantals made it out into the racks with barrels chambered in .223/5.56. I don't know if the case chamber dimensions were out of spec for 5.45x39, since I never heard of that being an issue of itself. Frankly if they were being sold with .223 barrels AND chambers I would think that would have created an accidental hot buy, but as it were I believe only the bore was out of spec on some of these early "oops" guns from Century.
If this has a Polish chrome-lined barrel then disregard my comment here, but it may be worth slugging/miking or doing a bullet test with a 5.45 and 5.56 round. Remember that the 5.45 round should not be able to be inserted all the way up to the case neck - please someone correct me if I'm wrong, I don't own any 5.45 rifles.