From what I’m reading, ammo not in a firearm during a house fire will “explode” (popping noise, but not projecting the bullet out of the casing, the casing explodes). However, ammo in a firearm during a fire will be sent down the barrel as if it had been shot. It appears that how you store the ammo will also make a difference (in a metal ammo box or in a safe).
@KevinM, do you have any insight on what happens to ammo in a home fire??
BTW, I changed the title of this topic to more closely reflect the direction of the topic. If need be we can spin up a separate topic as well.