If the ammo is small arms, then no, it would not increase the fatality number. Ammo “touching off” outside a firearm chamber does not fly off in a powerful manner or direction, because the exploding gunpowder creates the hot gases that expand in all directions, simply rupturing the cartridge. In contrast, for a cartridge firing within a firearm chamber, the heavy walls of the chamber and the heavy tight bolt behind the cartridge force the explosion only in one direction—down the open barrel. Cartridges just burning up and popping off are like firecrackers, essentially, and the bullets do not fly off and hurt anyone. The cartridges “cooking off” and killing bystanders by bullets flying off in a random manner in a fire is a myth.
Crap, somehow my entry above got posted here but was supposed to be in a thread about the sinking of the Lusitania. Sorry, guys.