Many years ago a client of mine destroyed his left hand after testing an 8mm with a hexagonal barrel, which, only after the incident were we told it had just been refurbished after going through a house fire.
He was test firing it on the hood of the Cruiser while we pulled his hippo ashore (shot with a different rifle). His left hand rested above the chamber, and took the full brunt of the exploding round, which he reloaded and admitted to them being hot loads!!! The pressures were too much for the already weakened barrel.
It's a LONG story.
Bottom line is DONT EVEN TRY AND FIX THIS...... throw it out!!!!
Some fire damaged guns can be saved, but it's well beyond the scope o' practicality, when it comes to your average Gun Owner... Personally, for the most part, I wouldn't even bother attempting to save a fire damaged Barrel(Unless it was something super rare)... I have saved and repurposed a few Fire Damaged Receivers over the years... After Annealing & proper Heat Treatment o' course... One factor most folks wouldn't consider, is warpage due to being through a fire...