That was good DD, with totally predictable results.

I think the same type of tests should be done by fire departments with cans of powder, pistol and/or shotgun, rifle powders and black powder - which are pretty much now all in plastic, although some might still be sold in steel cans.
A friend had a "trailer fire" while he was at rendezvous. Inside his trailer were "empty" 20 pound propane tanks and about 300pounds of black powder. Most of the black powder was in 25 pound plastic bags in heavy cardboard boxes, while 25 or 50 pounds was in steel cans. This was before the big switch to plastic by GOEX. 30 pounds of powder in cans did not ignite. Those that did, split the cans and made smoke, as-did the powder in the 25 pound plastic bags.
The propane tanks blew the roof off the trailer, according to the fire department. They did not know about the powder until after the fire was out, but did note a LOT of white smoke at times, mixed with the black smoke.
The fire was started by neighbourhood (trailer park) kids smoking in his shed beside the trailer. The fire moved from the shed to his trailer in the dry weeds. This was end of August.