i dont doubt that theyd have trouble at or around 500, at 300 it was very very hot, but they cool down quick enough even if theres an extra pause for reloading time, i think its a non issue, some of us have been there, and you cant carry enough ammo close enough or have enough targets presenting themselves to get there that fast.
What i'd like to see is if it has ever happened to anyone not trying to destroy the rifle