Here is the relavent portion of the Ohio Revised Code:
http://codes.ohio.gov/orc/2923
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2923.16 Improperly handling firearms in a motor vehicle.
(A) No person shall knowingly discharge a firearm while in or on a motor vehicle.
(B) No person shall knowingly transport or have a
loaded firearm in a motor vehicle in such a manner that the firearm is accessible to the operator or any passenger without leaving the vehicle.
(C) No person shall knowingly transport or have a firearm in a motor vehicle, unless it is
unloaded and is carried in
one of the following ways:
(1) In a closed package, box, or case;
(2) In a compartment that can be reached only by leaving the vehicle;
(3) In plain sight and secured in a rack or holder made for the purpose;
(4) In plain sight with the action open or the weapon stripped, or, if the firearm is of a type on which the action will not stay open or which cannot easily be stripped, in plain sight.
(D) No person shall knowingly transport or have a loaded handgun in a motor vehicle if, at the time of that transportation or possession, any of the following applies:
(1) The person is under the influence of alcohol, a drug of abuse, or a combination of them.
(2) The person’s whole blood, blood serum or plasma, breath, or urine contains a concentration of alcohol prohibited for persons operating a vehicle, as specified in division (A) of section 4511.19 of the Revised Code, regardless of whether the person at the time of the transportation or possession as described in this division is the operator of or a passenger in the motor vehicle.
(E) No person who has been issued a license or temporary emergency license to carry a concealed handgun under section 2923.125 or 2923.1213 of the Revised Code shall do any of the following:
(1) Knowingly transport or have a loaded handgun in a motor vehicle unless one of the following applies:
(a) The loaded handgun is in a holster on the person’s person .
(b) The loaded handgun is in a closed case, bag, box, or other container that is in plain sight and that has a lid, a cover, or a closing mechanism with a zipper, snap, or buckle, which lid, cover, or closing mechanism must be opened for a person to gain access to the handgun.
(c) The loaded handgun is securely encased by being stored in a closed, locked glove compartment or in a case that is locked.
(2) If the person is transporting or has a loaded handgun in a motor vehicle in a manner authorized under division (E)(1) of this section, knowingly remove or attempt to remove the loaded handgun from the holster, case, bag, box, container, or glove compartment, knowingly grasp or hold the loaded handgun, or knowingly have contact with the loaded handgun by touching it with the person’s hands or fingers while the motor vehicle is being operated on a street, highway, or public property unless the person removes, attempts to remove, grasps, holds, or has the contact with the loaded handgun pursuant to and in accordance with directions given by a law enforcement officer;
(3) If the person is the driver or an occupant of a motor vehicle that is stopped as a result of a traffic stop or a stop for another law enforcement purpose or is the driver or an occupant of a commercial motor vehicle that is stopped by an employee of the motor carrier enforcement unit for the purposes defined in section 5503.34 of the Revised Code, and if the person is transporting or has a loaded handgun in the motor vehicle or commercial motor vehicle in any manner, fail to do any of the following that is applicable:
(a) If the person is the driver or an occupant of a motor vehicle stopped as a result of a traffic stop or a stop for another law enforcement purpose, fail to promptly inform any law enforcement officer who approaches the vehicle while stopped that the person has been issued a license or temporary emergency license to carry a concealed handgun and that the person then possesses or has a loaded handgun in the motor vehicle;
(b) If the person is the driver or an occupant of a commercial motor vehicle stopped by an employee of the motor carrier enforcement unit for any of the defined purposes, fail to promptly inform the employee of the unit who approaches the vehicle while stopped that the person has been issued a license or temporary emergency license to carry a concealed handgun and that the person then possesses or has a loaded handgun in the commercial motor vehicle.
(4) If the person is the driver or an occupant of a motor vehicle that is stopped as a result of a traffic stop or a stop for another law enforcement purpose and if the person is transporting or has a loaded handgun in the motor vehicle in any manner, knowingly fail to remain in the motor vehicle while stopped or knowingly fail to keep the person’s hands in plain sight at any time after any law enforcement officer begins approaching the person while stopped and before the law enforcement officer leaves, unless the failure is pursuant to and in accordance with directions given by a law enforcement officer;
(5) If the person is the driver or an occupant of a motor vehicle that is stopped as a result of a traffic stop or a stop for another law enforcement purpose, if the person is transporting or has a loaded handgun in the motor vehicle in a manner authorized under division (E)(1) of this section, and if the person is approached by any law enforcement officer while stopped, knowingly remove or attempt to remove the loaded handgun from the holster, case, bag, box, container, or glove compartment, knowingly grasp or hold the loaded handgun, or knowingly have contact with the loaded handgun by touching it with the person’s hands or fingers in the motor vehicle at any time after the law enforcement officer begins approaching and before the law enforcement officer leaves, unless the person removes, attempts to remove, grasps, holds, or has contact with the loaded handgun pursuant to and in accordance with directions given by the law enforcement officer;
(6) If the person is the driver or an occupant of a motor vehicle that is stopped as a result of a traffic stop or a stop for another law enforcement purpose and if the person is transporting or has a loaded handgun in the motor vehicle in any manner, knowingly disregard or fail to comply with any lawful order of any law enforcement officer given while the motor vehicle is stopped, including, but not limited to, a specific order to the person to keep the person’s hands in plain sight.
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The provision for needing to leave the vehicle is for
loaded firearms.
There are other options in transporting seperated ammo and unloaded firearms than keeping them in the trunk (which would be difficult for trucks that only have an enclosed cab). 2923.16 (C) states, "
one of the following"