How Hot Is Too Hot???

[Big joe]

Something I have wondered??? When shooting a sporter weight bolt action rifle how hot can you fire a barrel before it starts to damage the rifling??? I was out with a friend a while back and while I wasnt paying attention he fired my 300 Win. 4-5 times pretty quickly. When I felt the barrel WOW! it was hot. Question is ... does that damage the rifling and if so ... how much?

Thanks for your info...