Dynamite can be set off by a bullet. Some explosives are pretty sensitive to high velocity strikes.Is there a bullet/explosive combination that would make this story plausible? I suspect the sniper would have been using a FMJ bullet (or maybe a HPBT for accuracy reasons), but what could you build a vest with that would explode on contact? I am not up on the current trends, but I would not think they would be using something like Tannerite in their vests. The only thing I can think of is that the insurgent had his finger on the trigger for the vest, and in some way he detonated it as he was shot.