DEZ Tactical does not provide the specific bore diameter outside of stating "the pulled-button rifling produces a superbly accurate bore diameter." To get a more specific answer on the bore diameter, I would recommend contacting DEZ Tactical Arms directly by phone or email.
Email: info@deztacticalarms.com
Gunsmith/Technical Support: (608) 547-9907
i did contact DEZ arms and was informed the bore DIA. is .312th. for the 7.62x39 caliber barrel!