In the UK there were specialist "gunpowder vans". A photo of one used in Wales for slate quarry work is at www.penmorfa.com/Slate/Tramways.htm (scroll down a little).
There were also standard gauge vans, these were wooden 4 wheeled vans covered with steel cladding. Seewww.brc-stockbook.co.uk/GWR_Spec_1.htm
Models have been made including kits of the narrow gauge ones. Seewww.modelrailways.tv/narrow_gauge/rolling_stock.htm (again scroll down). There are also some other makers of gunpowder vans.
Hamish
There were also standard gauge vans, these were wooden 4 wheeled vans covered with steel cladding. Seewww.brc-stockbook.co.uk/GWR_Spec_1.htm
Models have been made including kits of the narrow gauge ones. Seewww.modelrailways.tv/narrow_gauge/rolling_stock.htm (again scroll down). There are also some other makers of gunpowder vans.
Hamish