Two week trip Thru Nevada, Utah, Colorado and Montana Shotgun in the Truck Question

[senseibuddy]

So my coworker is a Nevada resident. He is fixing to go on a 2 week trip thru the states mentioned.
He wants to bring a self-defense shotgun with him, as he is not a hand guy type of guy.

I’ve been looking online for laws on each state. Looks like Nevada is not a problem.
Loaded in Utah might be a misdemeanor. Not 100% sure yet.
I didn’t see a law listed on the website i was on for Montana addressing the shotgun in the vehicle.

What is the easiest way for me to find this info out for him?

 

[Cochise]

I'd think a call to each state's state police headquarters would be a good place to start.