I am curious, what is the temperature threshold at which rifle barrels are ruined? I've seen people shoot to cherry red and then pick it up after it's cooled and shoot again like it's nothing, and i know when gunsmith sporterize old milsurps they use a torch on the sight blocks to desolder them. On the opposite end of the spectrum, Demo Ranch showed a campfire ruin the temper of ar500 plates so projectiles they would normally stop punched right through. So what's the threshold for barrel murder? Is the steel that much of a different composition from ar500? How do you know if you are going to ruin a barrel?