I would 'nt worry about your family being in danger of ammo going off due to the heat of the fire , the amount of heat needed to ignite the rounds , you would already have left the house. The velocity of a loose round not chambered will not have the velocity obviously, but could still be very dangerous and unpredictable. I would think the brass becomes more of the moving projectile of the two pieces , the brass being the lighter of the two in weight then the bullet.
But any how this is my own opinion without google's help lol. Google those questions and see what comes up..
In case of a fire get your family out safely, then go retrieve your guns. Even if your life depends on it and there is only a 50/50 chance of your survival. Throw them out the window just in case you perish in the fire. I will buy them . The money would come in handy. And if you survive, You never know what ratty hotel you might be staying at after the fire and might be needing the guns to save your family again.
NOTE; just kidding about the last paragraph, sort of