How would this work on a military base, or federal property?
You can't have a firearm in your car on a military base. I don't even think you can have one in your home on base. I think you must lock it up in a base armory.
It wouldn't. Federal law overrules, at least as a practical matter. The military takes a dim view of privately owned firearms. Although most bases will allow those living in on base quarters to have them, if they are registered with the Provost Marshall. Many bases also allow long guns used for hunting, even by local civilians, if hunting is allowed on the post/base. But they still have to be registered with the Provost Marshall.
Won't at all....title 18 USC prevails to the best of my knowledge. Posted items are considered contraband even if it's just a tootsie pop or blue socks. If it's on the list it's verboten. Commanders and Uncle Sugar get to make their own rules on their own sites pretty much.....