Barrel: How Hot is TOO Hot?

Bar-sto barrels states that 500F doesn't affect short term wear on a barrel and does not affect the heat treatment. They have more experience than I do and I am not familiar with the alloy to know what the annealing temperature is but I would never let a barrel get hot enough to discolor - which is what happens at 500F. Firing a bullet through a barrel that is that hot cannot be good for it due to the friction of the bullet. Now there are two issues with that much heat. The barrel will expand so the bore will increase in size, a little. The bullet jacket is a self lubricating metal but it looses some of that quality with heat. I doubt the two cancel each other out. In some rapid fire competitions a pistol barrel can get hot enough to discolor so it might be that pistol barrels erode less because of the straight chamber and bore. I don't think I am going to punish one of my guns to see what the effects are in the long term.
Keep 'em cool and keep 'em shooting straight.
 
Heat is absorbed/dissipated unevenly, it affects barrels dimensionally (at lower temps long before microscopic changes in atomic composition). One area expands, another is cooler, etc. Dimensional changes occur which affect barrel harmonics meaning the muzzle is at a different point in space as the bullet is released from the muzzle.

Most barrels are button-rifled, which induces stress into the steel from the cold-forming which is the process. Some manufacturers "stress-relieve" the barrels after, most do not (cost).

There's "too hot" to shoot accurately, and "too hot" where the rate of fire is so fast the plasma being released into the throat is cracking/damaging the steel. Different conversations.
 
Non contact thermometer

The laser aimed non contact thermometers work really well, and have gotten cheap like 30 40 bucks, maybe less.

I keep one in my motorcoach for checking tire temps on hot days with heavy load on the freeway.

Very handy item.
 
At the range today, the temperatures got to 95 degrees by about 10 AM.

The temp strip on my bull barrel, after letting the barrel cool down using the barrel cool fan, never got below the 95 degree ambient temp. I guess the temperature strips work.

But it didn't take many rounds down range (about 5) to get the barrel temp back up past the 122 degree mark and toward the 140 degree range.

Lots of time spent with the barrel cool fan inserted into the chamber this morning.
 
That was a question I would ask my shooting friends . Then I read an article on Accurate Shooter about McMaster - Carr temp strips that attached to a gun barrel . Ordered a pack of ten for $12.00 now my shooting friends just check the temp. strip. Takes the guess work out.
 
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