I was wondering how hot you can let the barrel get on an AR-15 type rifle/carbine before serious damage takes place.  I know with hunting rifles, you should be able to put your hand on the barrel for 10sec.  But with an AR type I would expect they go through a lot more abuse, and should be able to handle it.  I am just curious.  I guess another question would be, how many rounds would a typical barrel last?

I know some people hunt with ARs (I plan on hunting with my first one when I get it) so I apologize for any generalities I might have made.  I tried to do a search, but it kept getting zero results then I had to wait a minute before searching again, so I thought I would just post this question.  Thanks.

Red hot. Try bump firing 4~5 mags.
The gas tube will fail before you get close to any barrel damage.

how long will the barrel last though  surely it would start to deteriorate, wouldn't it??

If you take good care of it, the barrel will last past your grandchildren's life-time.

The more you bumpfire and heat up your barrel, the quicker you will burn it out.  It isn't a concern for most people, but there are plenty of us here who have gone through several barrels.  There is no way in the world that my children or grandchildren will be using my primary AR15 barrels.  They might be using the 2nd, 3rd or 4th barrel on them....