I think this section is applicable:
TITLE 21 § 1289.13. Transporting a loaded firearm
TRANSPORTING A LOADED FIREARM
Except as otherwise provided by the provisions of the Oklahoma Self-Defense Act or another provision of law, it shall be unlawful to transport a loaded pistol, rifle or shotgun in a land borne motor vehicle over a public highway or roadway. However, a rifle or shotgun may be transported clip or magazine loaded and not chamber loaded when transported in an exterior locked compartment of the vehicle or trunk of the vehicle or in the interior compartment of the vehicle notwithstanding the provisions of Section 1289.7 of this title when the person is in possession of a valid handgun license pursuant to the Oklahoma Self-Defense Act.
Any person convicted of a violation of this section shall be punished as provided in Section 1289.15 of this title.
Any person who is the operator of a vehicle or is a passenger in any vehicle wherein another person who is licensed pursuant to the Oklahoma Self-Defense Act to carry a concealed handgun and is carrying a concealed handgun or has concealed a handgun or rifle or shotgun in such vehicle shall not be deemed in violation of the provisions of this section provided the licensee is in or near the vehicle.