Been there, done that. 
Absent a barrel to confine the expanding gases into propelling
the projectile down the bore, the gunpowder in the
cartridge will just fizzle and pop the projectile a few inches
from the case.
The Hollywood stereotype of unchambered live rounds going off in
a fire and putting holes in the surrounding structures is mostly
bullcrap.
yeah.. the casing was the one which made most damage but it will
not be lethal..
however, the maniacs upped the ante... they dumped a beer keg
onto the fire.. and it went off like a bomb 
