I will only note that with MOST of the ULA and NULA rifles I have fooled with (and I have been shooting them for just about 20 years now) it doesn't make any difference at all if the barrel is cold, hot or smokin' hot. They still stack them into the same place. I suspect that any that doesn't has a barrel that didn't quitre make it out of heat-treating perfectly.

“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck