lack of concussion injuries? Ok.. that's fine and dandy, until you see the concussive shockwave alone (not causing bodily injury with flying bearings or metal) still knocked a runner on his ass after his knees completely buckled. What's the max PSI that said pressure cooker can take? Was it truly designed to be a directed blast, or did it turn out to be weaker around the point where the lid would seal and just appear to be a directed blast? (physics says this would be a yes - the lid/seal is definitely weaker - especially in terms of quick/hella fast expansive pressure, as pressure cookers aren't designed to handle immense pressure compared to a few other designs) Am not arguing, just stating that it looks to be more than just a bit a bit of low pressure explosive used.. given that the forensic photos by no means showed any sort of a cone, or device capable of directing the blast out.. and as such, probably sprayed bearings out the sides as well. At this point, short of seeing the mass spec / gas chromatograph results and trajectory calculations based on where the devices are.. this is pure speculation and is open to debate / your own interpretation.
Well, it could have been a sealed bomb, like an artillery shell, I guess. But, I think the idea is the cooker vent gases at a low temp in fridge. The flakes build up a inch or so of explosive on the flat bottom.
He can prepare a load, maybe 1 pound of metal and 2 pounds of clay. Use the lid of the pressure cooker for his form.
When everything is still very cold, CAREFULLY, push down the charge onto the explosive.
I don't think he put the lid back on. I don't think it was an omni-directional blast.
And the one runner that collapsed may have taken a couple of ball bearing in the gut. Those we not ground shaking explosions, looked to me.