Recommended max barrel temp

[Dosh]

I've searched the net but haven't found a specific answer. When firing a bolt rifle at the range, what is a safe max temp reached indicating I've reached the cut off point to let barrels cool. I've read many threads about "if it feels as hot as a", but not a specific temp. I have a digital thermal thermometer, the point and read type. Does anyone have a number in Fahrenheit or Celsius. Just like vision or hearing, everyone is different so one's touch may vary. I've made a barrel cooler from a battery air mattress pump which cools a barrel very quickly, but i don't want to wait till the barrel is over max temp to use it. How about it all you "thermo-molecular physicists"?
Thanks in advance for replies

 

[jrock]

I've done some temperature testing like you are hinting at. I did it on a hot summer day with no shade and found that waiting about 4 minutes between shots (#3 contour) kept my groups consistent. I used an inferred thermometer to measure the barrel temps while doing this and noted that the temperatures changes significantly along the barrel length. I picked a point just short of the end of the forearm where it seemed to be the hottest and monitored the temperature. I don't remember the numbers off the top of my head but I did write them down.
That being said, I would let the grouping tell you when the barrel is too hot rather than go off a barrel temp. Temps will change on many different conditions and contours. Not coincidently, the stable temperature that gave good groupings was "warm" enough that you could hold onto the barrel without discomfort.

 

[Dosh]

j, I've read a lot of post very similar to yours. I'm looking for hard numbers, whether from manufacturers or a shooter who has performed semi-scientific tests. Not picky about whether temp number is Fahrenheit or Celsius, the infrared thermometers have both.

 

[jrock]

Dug up my numbers and the consistent temperature reading was between 90 and 100 degrees. Not semi-scientific or anything. Just did it for fun.

 

[FearNoWind]

... what is a safe max temp reached indicating I've reached the cut off point to let barrels cool

I can't define "safe" with respect to rifle barrel temperature. Some stories of military engagements at various points in history tell of machine gun barrels getting red hot and still firing ...
During matches I sometimes fire 30 rounds inside of fifteen minutes and never experienced any malfunctions at the shooting position. But with that kind of torture my rifle does tend to display groups on target that are sometimes disappointing.

 

[Barrelnut]

Dosh, think I understand what you are getting at but there are so many variables, especially if barrel life is the objective.

For a barrel starting to walk, temps would vary, and a lot of it would have to do with particular stress points and metallurgy of each barrel. Every barrel on the planet would be a little different.

Now, it might be a good idea to record temps on a barrel after, say two shots, and the temp when it stared to throw flyers. Then you would know when to back off and let it cool.

I have a cooling system just like yours. I usually shoot until heat waves from the barrel start creating enough mirage to affect the sight picture in the scope. Then quit shooting and run the air pump for about 15 minutes.

Have a laser temp gun too. Now that you have brought this to my attention, think I will try to record the temps where these things start to occur.

 

[Dosh]

Dosh, think I understand what you are getting at but there are so many variables, especially if barrel life is the objective.

For a barrel starting to walk, temps would vary, and a lot of it would have to do with particular stress points and metallurgy of each barrel. Every barrel on the planet would be a little different.

Now, it might be a good idea to record temps on a barrel after, say two shots, and the temp when it stared to throw flyers. Then you would know when to back off and let it cool.

I have a cooling system just like yours. I usually shoot until heat waves from the barrel start creating enough mirage to affect the sight picture in the scope. Then quit shooting and run the air pump for about 15 minutes.

Have a laser temp gun too. Now that you have brought this to my attention, think I will try to record the temps where these things start to occur.

Good reply, several of us here have been discussing this a lot lately. With daily temps here well over 100, we are planning a trip to the high country (6500') to shoot for a day. I will keep record of the temps on possibly 10 or more bolt hunting rifles. I agree contour, metal type, length and caliber are variables. The air pump cools a barrel quite quickly and the batteries seem to last a long time. I've seen military barrels practically melted, but not my obvious goal. Will post my readings when we return.

 

[dok7mm]

Dosh, I really can't add anything to the above suggestions, but I never run strings exceeding 2 shots, normally just one shot. I then cool to ambient temperature. All my rifles are customs and barrel life is my main concern. I'm usually testing something and feel I get better results with this method.

I have a temp strip on the chamber, but it's rarely the warmest area. I also use a infrared temperature gun to monitor barrel heat and turn on the barrel cooler as soon as I extract the fired round. In cold weather, the wait time is usually pretty fast, but right now it takes awhile.

 

[BallisticsGuy]

There's a reason the rule of thumb is "hot to the touch". That's actually a pretty narrow temp range. If we pull all the manly man nonsense out, we all have nerves and they all respond in about the same way to about the same thing. Roughly 110F would be considered hot to the touch and you won't want to hold on to it long. In terms of the metal, every BTU of heat soaked into the barrel will make it easier and more likely for your next shot to substantively damage the throat. As soon as the barrel hits about 90-100F I'd seriously pull the bolt out and let it cool naturally. I don't like rapid cooling and don't advocate it.

I used to do a bit of a different rule. 3 shots for a skinny barrel. 10 shots for a 1.25" super heavy, 5 shots for a normal 1" bull. Worked well but was affected greatly by ambient temps.

 

[Edd]

I don't understand these 90-100° F comments. This discussion is about barrel steel. 90-100° F is barely comfortable bath water temperature. Many people would consider it too cold to be comfortable. I have never monitored barrel temps but I am familiar with many applications where metal continuously operates at ~ 250° F. I would think safe barrel temps would be similar to that.

 

[BallisticsGuy]

I don't understand these 90-100° F comments. This discussion is about barrel steel. 90-100° F is barely comfortable bath water temperature. Many people would consider it too cold to be comfortable. I have never monitored barrel temps but I am familiar with many applications where metal continuously operates at ~ 250° F. I would think safe barrel temps would be similar to that.

Because you're thinking about the metal's capabilities which are, honestly irrelevant to the rule of thumb.

The idea is to NOT reach excessive temperatures. It is to STOP SHOOTING long before that point is reached. Unfortunately, the difference to the mark-1 finger-tip thermometer between 100F and 120F is the difference between hot and plenty hot, there's no quantifying high temperatures using a finger/hand so the slop is HUGE.

The difference between 120F and any hotter on the other hand is basically lost on humans since skin burns ensue pretty quickly after 120F so they (fingers/hands) don't have the ability to usefully measure the heat when it's over their skin tolerance threshold. Rather than change the rule to "when your skin sticks to the barrel" or "use a thermometer checking for the approach of X temperature" we do it the easy, reliable way. Besides, to call out a specific temperature would require knowing a TON of stuff about the barrel, powder, bullet, environment, etc...

Some things it pays to quantify and get things exactly right. Others it pays to heed 100 years of collected experience even if it is nothing but anecdotes and rules of thumb. Don't toss the baby out with the bathwater.

 

[Edd]

Because you're thinking about the metal's capabilities which are, honestly irrelevant to the rule of thumb.

The idea is to NOT reach excessive temperatures. It is to STOP SHOOTING long before that point is reached. Unfortunately, the difference to the mark-1 finger-tip thermometer between 100F and 120F is the difference between hot and plenty hot, there's no quantifying high temperatures using a finger/hand so the slop is HUGE.

The difference between 120F and any hotter on the other hand is basically lost on humans since skin burns ensue pretty quickly after 120F so they (fingers/hands) don't have the ability to usefully measure the heat when it's over their skin tolerance threshold. Rather than change the rule to "when your skin sticks to the barrel" or "use a thermometer checking for the approach of X temperature" we do it the easy, reliable way. Besides, to call out a specific temperature would require knowing a TON of stuff about the barrel, powder, bullet, environment, etc...

Some things it pays to quantify and get things exactly right. Others it pays to heed 100 years of collected experience even if it is nothing but anecdotes and rules of thumb. Don't toss the baby out with the bathwater.

The OP was asking about using a thermometer, not his finger. A pull the bolt and let it cool at 90-100° recommendation seems a bit ridiculous to me.

 

[dok7mm]

Ballistics Guy, most of the pump type barrel coolers being used are not "rapid coolers" unless someone runs a couple of loops of hose thru a container full of ice water. Generally, it is moving ambient temperature air thru the action and barrel. At our current 95* temps, my pump cools the barrel in about 10 min. instead of 15 min. I do see where very rapid cooling to sub-ambient temperatures would be a no-no.

 

[Deleted member 46119]

I put temperature strips on a lot of barrels.

I notice accuracy changes starting at ~130° surface temperature. I have not been able to determine the internal temperature. 130 is "hot to the touch" which is the "rule of thumb".