man, i cant even imagine how hot it gets. why do you think it is called "hot lead". first, it is being FORCED into the rifleing, then shoved out of the barrel, and the longer the barrel, the longer friction has to do its work, PLUS it is coming down the tube at a blistering pace. i know it happens at a horrific speed, but when there is that much force involved, it has to transfer heat. i don't think that much heat would transfer INTO the bullet from the burning powder, the back face temperature would probably increase, but it happens so fast, that it wouldn't affect the overall temerature of the bullet.