Just read a big story about the Iowa explosion, and yes, it WAS black powder. Hard to believe, in this day and age, but the big guns DO use BP.
Have to go to my bookmarks, think I kept it, will post to this thread for anyone interested, but it was a mistake of either an overcharge, or an undercharge, leaving airspace, I think. Can't really recall, will have to reread..
They rammed the projectile then the powder charges, say 4 charges where it will hold 6, and load 2 dummy charges first then the 4 BP charges and ram tight. No air space, just as is preached in BP revolver and rifle shooting.
IIRC, they didn't use the makeup dummies and it blew. Wasn't murder/suicide by the boy who was homosexual.
Have to find and reread.
Cheers,
George
edit: To propel this heavy projectile forwards, the gun required six bags of black powder!
"....on that fateful day, the Navy bosses decided to use five bags of a different propellant instead (a high explosive technically known as D846). Each of these bags weighed 94 pounds."
http://www.geradts.com/anil/ij/vol_003_no_001/reviews/pb/page004.html
That link is to a book review about the Sandia Labs investigating the explosion.