The first batch that came in had serial numbers on the upper (underside of the FA) that were no where near the rest of the gun, and the uppers were full auto - like they'd just pulled them off another production line and plonked them on civi lowers. The first batch were definitely 5.56mm. I'm surprised no one ran any of that PMC M855 that TSE had through a Norc. If anyone from TSE is looking at this, we need more of that - but given the current circumstances in S. Korea I doubt there's much surplus at the moment.