John what he says about the barrel metal melting is apparently true. He is talking microns in thickness and for less time than the flame is there. Hence throat erosion. From what I have read it is not so much on the first firing but more so on subsequent shots while barrel is hot. Takes a fair amount of powder or many shots to do this. The Bren gun had a chromed lined bore and did not suffer throat erosion like some other machine guns.

As you say, not likely to happen in a sporting situation unless you are bombing up a mob of pigs.