There are NO Federal restrictions on carrying a loaded firearm, while operating a commercial vehicle! The only restrictions are on the cargo, which states "no 'loaded' firearms may be contained in the shipment". More of a restriction on the shipper. I have researched this extensively.
Actually,thats not true.The rules clearly state that a weapon may be in a commercial vehicle if your permitted in that state and the weapon is unloaded and the ammunition must be separated so that it is not easily accessible.
TITLE 18–CRIMES AND CRIMINAL PROCEDURE
PART I–CRIMES
CHAPTER 44–FIREARMS
Sec. 926A. Interstate transportation of firearms
Notwithstanding any other provision of any law or any rule or
regulation of a State or any political subdivision thereof, any person
who is not otherwise prohibited by this chapter from transporting,
shipping, or receiving a firearm shall be entitled to transport a
firearm for any lawful purpose from any place where he may lawfully
possess and carry such firearm to any other place where he may lawfully
possess and carry such firearm if, during such transportation the
firearm is unloaded, and neither the firearm nor any ammunition being
transported is readily accessible or is directly accessible from the
passenger compartment of such transporting vehicle: Provided, That in
the case of a vehicle without a compartment separate from the driver’s
compartment the firearm or ammunition shall be contained in a locked
container other than the glove compartment or console.
http://askthetrucker.com/cdl-federal-gun-law/