"From my research I have not found any source to say finely ground smokeless powder will detonate."
I haven't either, but didn't look very hard. I said "Very light loads of fast burning smokeless powders in large capacity cases MAY create very high pressure."

re: SEE. Google Dr. Lloyd Brownell Secondary Explosive Effect and you'll find pages of light reading, with no definitive answers. There are impressive images of blown up handguns and rifles however.

And shotguns, the cause of which has not been explained

[Linked Image from photos.smugmug.com]

You might google Grain Elevator Explosions too. I'm sure you've seen some in Alberta. There was a major explosion in Wichita in 98' and Atchison in 2011

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