I know that the subject of barrels has been one of many a topic.  I am curious as what the different metals work best in a barrel?  I am leaning towards a chrome line barrel or an unlined barrel and staying away from stainless.  I was talking to an engineer who uses quite a bit of stainless in fabrication and he was telling me that stainless warps rather easily with changes in temperature.  If this is indeed true, what would prevent a heated up barrel stainless steel barrel from doing the same thing?  

My apologies if the question is a rehash, I am getting ready to order my first AR-15, I have everything selected except for the barrel material.  I had thought I had that part selected until discussing/ getting a lesson 101 on metallurgy.  Appreciate all input, experience, advice.  

Wally