Most campfires are build with a pit made out of rocks or stones, so if you dump your bullets in just a plain old fire the bullet will fire, but if the fire pit is made with rocks or stones and the bullet should just end up next to a large rock this would make the bullet work as it would in a gun,very deadly..I would not suggest that anyone would do this, while sitting around a campfire.

Tested and busted.
Unless the rock it was next to, had a hole through it to form a chamber and barrel and the round was inserted inside, and then the cartridge case end closed off to form a breech.

The bullet part being relatively heavy, surely that would tend to stay put, while the case, being lighter and flimsier, woul head off in the opposite direction?
Thinking back to the "Bullet used as a fuse" episode, I am lead to think that it could have been the cartridge case that was propelled at the drivers delicate area, probably without enough force to penetrate trousers and skin, but enough, combined with the unexpected noise, to distract the driver from giving his full attention to the road.

Makes sense to me too, Malcolm

Malcolm
I think you missed my point, I would like to see what the bullet would do if the cartridge case was up against a solid rock,the case would have no where to go, unless the shell split first, just a thought before someone thinks that "it's funny to throw a bullet into a fire pit" is all.

The cartridge case splits; it's as simple as that.
One of my jobs in the past was to incinerate unserviceable ammunition.
Also, in all the ammunition accident investigations I have conducted, in which the round has functioned outside the chamber, the cartridge case has split.