Barrel: How Hot is TOO Hot?

R

RC20

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AMENDED: 308 Bolt Action, bull barrel, XC, Lower Level Loads 168 Grain:

Normally I keep a feel on the barrel, but I was zone in and shooting quite a bit.

Unusually warm day for us (75, don't laugh and 75 in AK is a lot hotter than anyplace other than Humid areas) and sun was hitting the barrel as well.

I found it almost too hot to touch.

I know 180 degree is too hot to hold on for long.

This was getting close but not there. Call it 150 or so.

Is there any general direction or thoughts on how hot is too hot?

I was slow shooting, but semi steady.

Next time I can put it in the shade during time out and pull the bolt and cool it off more but curious on any thoughts.
 
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It might be helpful to know the gun and caliber you are asking about but at 150 degrees it probably doesn't even matter. Unless you're shooting some very worn out antique from the 1800's I wouldn't worry about any damage.
 
Hot?.......It doesn't even cool off to 75vwhere I am............A/C's been running since May 1.

For me, whether from heat and sun or firing; if I can't hold it for a second, I let it cool off. (Not talking about serious target rifles or pistols)
 
The type of rifle does matter. If it is a precision rifle then too hot can speed up erosion of the rifling near the chamber. If you're talking about a military style semi-auto then it could still do the same damage, but on that type of rifle a small loss of accuracy isn't a big deal.

I don't like to let my hunting rifles get too hot to touch. Not that I'm worried so much about damage, but a hot barrel will change POI. The hotter the barrel gets, the longer it takes to cool off. Usually 3-5 shots with 30 second spacing between shots is all I want to take.

The outside temps play a role. At only 75 degrees it will take longer for the barrel to heat up, and it will cool down faster. Our low temp hasn't gotten down to 75 in several days. Today was a cool day, only reaching 95, but with 100% humidity and rain.

I've shot at the range when it was 105-110 and the barrels do heat up faster and it takes a lot longer to cool them off. Some guys drape a wet towel over the barrel with the rifle sitting on the bipod to help. As the water evaporates it cools the barrel. I've left the truck running with the AC on and placed rifles in the front seat to cool them off within a reasonable time to get in another string of shots.
 
I like both ideas

Car A/C (yes, we have it, we aren't wimps, 75 in AK has more direct light and less atmosphere than lower 48)

Towel would work, barrel are stainless.
 
I didn't say it but interested from fall off in accuracy.

Still in that stage where sometimes I shoot a heck of a group and other times it spreads out with the same load.

Its not like I am an MG42 firing rate wise.
 
You can find some crazy videos on UTube where shooters fired their AK47's to the point that the handguards burst on fire!. That is too hot.

I have fired surplus 8mm through M98's Mausers so fast that any metal part on the barrel, such as the sling swivels, receiver ring, rear sight, were hot enough to cause a burn. I then opened the bolt and poured water down the chamber, barrel pointing down, which always on first pour, caused a geyser of boiling water to blow back out the breech! I would wait for the geyser to stop, pour more, until everything cooled down, and then, I began the rapid fire fun again! I figure the barrel temperature was above 212 F.

Rapid fire shooting will eat up barrel throats. Rattle battle rifles had short barrel lives. You could look up the annealing temperatures of chrome moly steels, but it is probably above 500 F, you heat the barrel up to those temperatures, I don't think anything good is going to come out of the experience. Barrels are not heat treated like knife blades, or bolt lugs and receiver seats, but, I don't know enough about them to recommend getting up to annealing temperatures. There are people here who know more about the subject.

If the barrel is hot enough to feel hot, don't worry. Let it cool down so that if you touch it, it won't burn you. If the barrel is glowing cherry red, I would consider that very bad and I just don't know if the barrel is good once cooled.

Still in that stage where sometimes I shoot a heck of a group and other times it spreads out with the same load.
Click to expand...

Might be you, might be the gun.I do have rifles which the point of impact changed as the barrel heated up. These rifles had pressure bedded barrels. Now they don't and I shoot them till the barrel is hot when testing ammunition. I don't see group size increases just due to barrel heat. I do see group size increases due to shooter fatigue, and I see that all the time. The human factor is the least controllable accuracy element and the one that causes the greatest inaccuracy. This is something ignored in the popular press. I can say by the time I have entered the 45 stage of the Bullseye Pistol match, I am bucking and flinching, and my groups are horrible. I don't know how the good pistol shooters control the flinch reflex. Bullseye pistol is just impossible. :(
 
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When I am load developing, I don't let the barrel get more than 15 deg warmer than ambient temperature with rifles.

120 degree water is hot enough to cause a 2nd degree burn. I am sure that a 150 degree barrel would be to much to bear for me.
 
Precision rifles: Reach up and touch the barrel below the scope around the chamber area. If I can't hold a finger on it for more than 2-3 seconds, I let it cool down.

Battle Rifles: let it cool down after 50-100 rounds of continuous fire.
 
As far as getting too hot to the point of affecting accuracy, I don't know all the answers.
Good barrel steel, that rings like a bell, is stiffer and warps less, in my opinion, than the stuff most used today, with sulfur and lead in the metal, for easy machining.
The good metal erodes a lot less under lots of rounds. Yes sulfur, and the lead will try to burn out of the metal at sufficient high temp.
A barrel with cut rifling, as supposed to the almost universal hammer forged, will warp less too. Hammer forging moves the metal around a lot and induces a lot, of potential for warping. I don't know how much stress relieving they do after the hammer forging, but reasonable assumption is not enough as it would affect the accuracy out of the box.
A free floated barrel, with correct heat treatment before rifling and so on, with no slings or swivels, on the barrel, will probably be the best option.
The barrels used by thousand yard competitors, would be the barrel makers, I would look at. Most ,of those barrels are thirty inches up, to even thirty four inches, so they must be doing it right, as all that length would leave plenty, of metal for warping potential from the heat of firing. I don't remember any of the barrel maker names at the moment.
You still won't be able to fire ten shot strings with total accuracy unless it is a twenty two.
Center fires burn a lot of powder and the big magnums a hand full or more.
Only way is to shoot and note. If impact moves after five shots then you know to let it cool. An infrared handheld thermometer will easily let you know at what the temps are from the breech, to the muzzle.
 
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Too hot for what? We used to fire 2 20 round mags out of our C1A1's, rapid(as fast as possible.). That'd cause the wood forestocks to smoulder. One mag of 4 rounds out of a typical bolt action hunting rifle fired slow but steady is enough to cause the barrel to be too hot to touch. So is a mag load out of a .22.
75 F isn't hot, but if you left a rifle in the sun anywhere at 75 F, the barrel will get too hot to touch too.
"...sulfur and lead in the metal..." There's no lead or sulfur in steel.
 
From actual measurement - air temperature 70F. in the trunk of a white car temperature reached 150F !!
I mention this so you can give thought to protect ammo when target shooting. Low cost Styrofoam boxes I use to keep ammo at a more reasonable temp!
 
I have LCD strip thermometers on each of my target rifles. They read from 88 to 140 degrees or 88 to 194 degrees. The strip thermometer manufacturer suggests that 140 degrees barrel surface temperature is about where you should stop shooting and let the barrel cool.

140 degrees barrel outside temperature is really hot to the touch and probably too hot in the chamber to risk excessive erosion. IMHO, it isn't worth damaging a great shooting rifle by being impatient.

When the temperature on the outside of my bull barrels on my target rifles show more than 122 degrees F, at least two of my best shooting rifles have their point of impact drop about 1/4 inch from point of aim. That makes a significant enough impact on my group sizes that I find it is a good place to stop and allow the barrels to cool. I suspect that the internal temperature is even higher, especially in a fluted bull barrel.

I tend to stop shooting when the LCD thermometer approaches 122 degrees and put a barrel fan (barrelcool.com) into the chamber and let it run for about 10 minutes. The fan reduces the cooling time about in half, even in high ambient temperatures.
 
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