I never let my barrels get that hot.I usually shoot three and switch to another rifle while that one is cooling.Heat is a bad thing for barrels.So it like this,say you have a 308 Win and your burning say 45grs of powder and your have say a 300 Win Mag and your burning 75grs,that 300 Win Mag is going to get a lot hotter.

~Molɔ̀ːn Labé Skýla~
As Bob Hagel would say"You should not use a rifle that will kill an animal when everything goes right; you should use one that will do the job when everything goes wrong."Good words of wisdom...............