Can’t say much about the specifics of loading and unloading, but I know when I worked in the Harriman Dispatching Center we moved explosives all the time. Placarded explosives 1.1 or 1.2 and I believe the explosives and detonators have to be transported separately.
I remember a rush movement of ordinance when they were going to invade Panama in 1989. Just several cars in a special movement to Houston (I think.) Explosive type items are moved often enough it’s no big deal as long as the cars are properly placed in train according to each railroads Hazmat instructions.