Went shooting 6mm Remington yesterday trying some new loads at 200 yards and just happened to have my laser temperature gun with me. After shooting 10 rounds slow fire I checked the barrel temp at the throat area and it read 109 degrees and the end of the barrel read 107 degrees with OAT at about 90 degrees. This got me thinking about what the max temperature a barrel has to be before accuracy starts falling off. I've never seen any data on this. Has anyone done their own research to see what the magic temperature is?