If a round is not sufficiently encased by a chamber, the bullet will go nowhere as the brass or steel splits and vents. In one "oops" I read about, when someon

If a round is not sufficiently encased by a chamber, the bullet will go nowhere as the brass or steel splits and vents. In one "oops" I read about, when someone was in too much of a hurry to finish a "bullet board" (a display of cartridges on a board), they used a drill on a loaded round to to make a hole to get the powder out (also makes it clear the round is not loaded), holding the round with their fingers. No, that's not a good idea; even if their fingers didn't feel the heat generated by the drill quickly enough, it was sufficient to set off the primer, which embedded itself into the guy's bicep. And the case split, but only spilled unburned powder on his hand, that situation wasn't enough to set it on fire or otherwise harm him. So I tend to assume it's more of an accelerant problem than a primary fire hazard, especially since as far as I know, loaded cartridges with sharp, pointy bullets but also with extra hard military primers as sometimes sold and shipped in bulk packaging, "loose" inside a bag (! see e.g. http://www.natchezss.com/federal-5-56-62gr-fmj-green-tip-600-pk.html http://www.natchezss.com/federal-5-56-62gr-fmj-green-tip-600...). That doesn't give me a warm and fuzzy feeling, but apparently the biggest US ammo manufacturer, many distributors, and the US Department of Transportation and UPS are OK with shipping that by ground.