I think P.T. was describing something akin to a miniature fuel/air bomb of a similar variety to what was used in the OK City bombing. There was a dispersant/atomizer and a subsequent igniter. There was also a similar methodology used in Viet Nam.
In relation to the S&W forum issue, it seems to be predominantly a rifle phenomenon, involving slow burning powders with not too greatly reduced loads.
In handguns, it seems more likely that double or even triple charges and/or multiple projectiles and/or bore obstructions account for most Ka-Booms. Other factors can be involved, so the list doesn't have all the possibilities, but there were sufficient "and/or" to get the point across.
