mikiep, I'm afraid you've asked the wrong guy. You'll need to touch bases with those in the firefighting field and fire protection field about that, and I ain't one of those guys.
That said, though, flame resistance ain't one of my own priorities in firearms selection. Stuff I can't afford to lose if my house burns is in my safe deposit box, 'cause I hope the damn bank is more fire-resistant than my home...
Can't resist adding this: