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How hot is too hot for a barrel?

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?
 
Don't really know. I've used a laser and a stick on thermometer before. Now I just use my hand. If I can hold the barrel near the chamber without it being uncomfortable (probably 95-105°) it's ok. I also use an air blower and let it blow through the open bolt down the barrel. Usually even on really hot days, 30-60 seconds brings the temp right down between shots. Just don't leave a round in the chamber for longer than you have to. Some powders are very sensitive to temperature.
 
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?

109 degrees is nothing for us here in Arizona; when it's 115 in the shade all you have to do is let your barrel sit on the bench for 15-20 minutes and you've got 120 degree barrel to contend with.

There is a positive aspect to the heat, I just cleaned a load of brass, 45-50 minutes in the sun and everything will be completely dry.
 
A few years ago I taped the temperature probe to my digital thermometer four inches ahead of the the chamber. As in competition I fired 10 shots of 7-08 in about five minutes. This test was fired from a bench rest at a 300 meter gong. Shot 7 thru 10 reached and maintained 154 degrees F with no ill effects on accuracy. The barrel returned to ambient air temp in about 12 minutes, around 90 F. This was a 24" sporter weight stainless barrel.

I will add that this and another barrel like it have 5700 rounds fired each to date and still print 1/2 MOA.
 
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109 on a 90-degree day isn't much (IME) that would be near a base line starting temp for me.
At 90 ambient, +130 from a HV tapered barrel is about as hot as I like to see them.

Shooting test strings fast, often is the most efficient way I find to beat barrel heat.
Allowing the barrel to cool down below base line temp before running the next test/string.
The size of the strings (test) is the dominate aspect to consider and plan for - IME.
Donovan
 
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Something even more important that barrel cooling is shooter cooling. I don't do so well when my glasses are steamed up and my eyes burning from sweat. Add the direct sunlight and the bugs in the field and it's near unbearable. I now have a large 6' diameter umbrella, a high volume air pump for the rifle barrel and an 8" clamp on fan for me both powered by a 12v jumper box. And a can of bug spray! Still can't hit but I'm more comfortable missing.
 
My son and I each shooting 20 rds. back to back relays at F-class match for a total of 80 or 120+ rds. I know barrel gets so hot you can't touch it. This is a 6.5x284 with 700+ rds. down barrel. Can't see any firecracking with cheap Lyman borescope, barrel cleans very easy too.
 
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?

What do you consider "slow fire"? I've got a half dozen rifles I've got to do ladder tests for and I'm concerned about overheating the barrels.
 
Competition pistol barrels are known to discolor from heat. That takes about 500F so you can get a barrel pretty warm without short term damage. Long term accuracy may suffer but I haven't seen any real studies done to find out. In making springs the last temper is done at 550F with a quick oil quench. All that does is take the brittleness out of the hardened spring. There is a big difference in the two steels but I doubt getting it that hot once will hurt a barrel.
 
I bought some temperature indicating labels from McMaster-Carr Supply website. They are self-adhesive and fit very nice on the barrel. They show the temperature from 86 to 140 degrees. They also have other temperature range labels.
 

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