How careful are you about not letting the barrel heat up?  My 16" HBAR and my 20" barrels will heat up quite a bit depending on the firing rate/outside temp/etc.  When I originally started shooting, I was told that a good general rule was to not let your barrel heat up so much that it becomes too hot to hold.  I realize that people who aggressively clean the barrel end up causing more wear than from bullets, but I would like to know your thoughts.

I am going to assume that neither of your ARs have match barrels on them.  If that is the case then you can ignore your "rule of thumb".  I have never shot any AR that I own and not had the barrel become to hot to hold during a range session.  All of my barrels have chrome lined bores and chambers. I have one upper with over 16,000 rounds through it that will still shoot a 6" group are 100 yards from a rest. I generally shoot 90 rounds in the course of an hour when at the 100 or 200 yard firing lines, that time includes setting up targets.

The Azalin