When a safe goes through a fully developed fire the heat activated door seals will swell up and seal the door quickly (assuming they are good quality). Over time, the peak internal temperature will gradually climb up to about 220-230 degrees F and then plateau for awhile. The peak temperature will remain at that 220-230 degrees F range until all the moisture is cooked out of the sheetrock fire lining. I say "peak" because there is usually about a 80-125 degree F difference between temperatures at the top of the gun safe and at the bottom. (Depending on height of safe and design)...Read More...