how do you measure barrel temperature in a reliable manner?

Professor Doolittle

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Any of you guys know a precise way of measuring barrel temperature? We've tried touching the barrel in a consistent place with a thermocouple and we've tried laser thermometers, but both of these are on the outside of the barrel and we have no knowledge of the thermal conductivity of steel. How is heat actually traveling through the barrel and how long does it take? I haven't seen a pro article that addresses this even though barrel temp definitely effects muzzle velocity and if you punch in muzzle velocity differences into a ballistics calculator you see it doesn't take much to add several inches of error to a target 1000 yards away.
 

StanleyActual

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I don’t. But if I had to. I’d use a temp gun.

I just fail to see what that informations does for you, other other than make you aware of what the barrel temp is.

Seems fairly useless beyond that, if you’re then going to try and dive into the details of how that temp correlates to specific velocity changes / POI changes. Of course your could use your Chrono to see how much temperature increases the MV but it’s wasted time better spent elsewhere in the shooting process IMO

personally, when you consider all the others. factors that are involved with making the shot. I’d say its pretty insignificant .

Just don’t shoot when the barrels hot
 
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FEENIX

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I don’t. But if I had to. I’d use a temp gun.

I just fail to see what that informations does for you, other other than make you aware of what the barrel temp is.

Seems fairly useless beyond that, if you’re then going to try and dive into the details of how that temp correlates to velocity increases / POI changes. Of course your could use your Chrono to see how much temperature increases the MV.

personally, when you consider all the other factors that are involved with making the shot. I’d say its pretty minimal.

Just don’t shoot when the barrels hot

Agreed!
 

BallisticsGuy

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Again with the tyranny of the discontinuous thought process and this is compounded by the mental error of making a mountain out of an ant hill. Ughh. The short and sweet answer is, you're overthinking things. The long way is below.

First: Continuous non-linear processes like thermal conductivity through an irregularly shaped mass cannot be spot measured from one small place on that mass and then that measurement used to determine how some other continuous process will develop. This is why we use large sample sizes in experiments that seek to determine the kind of relationship you're wanting to define. The error bars in the data end up larger than the effect you're trying to measure.

Second: The muzzle velocity difference between a round baked in a hot chamber and a round not baked in a hot chamber is absolutely meaningless to a ballistics calculation outside of really seriously extreme circumstances of silly long range and silly small target size and silly large case capacity. Before wasting a single moment of thought on this, figure out the maximum change to your trajectory and compare that to your target size. If the maximum velocity difference you can obtain experimentally is insufficient to exceed your target size then your target size is greater than your danger space and any measurement along these lines is a complete waste of effort. If the drop delta is larger than your target size then you need to get closer by definition.

If you wanted to measure such a thing directly then you simply want to do something that's essentially pointless. When you get up to huge cases like .338lap and the cheytacs and BMG based stuff then the powder capacity is so huge that you can, under pretty extreme conditions, see deltas in velocity that are important enough to bother wondering about but by that time the distance has grown to something really properly silly. Pretty much if you're needing to worry about it, you're doing something objectively silly.
 
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antelopedundee

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Again with the tyranny of the discontinuous thought process and this is compounded by the mental error of making a mountain out of an ant hill. Ughh. The short and sweet answer is, you're overthinking things. The long way is below.

First: Continuous non-linear processes like thermal conductivity through an irregularly shaped mass cannot be spot measured from one small place on that mass and then that measurement used to determine how some other continuous process will develop. This is why we use large sample sizes in experiments that seek to determine the kind of relationship you're wanting to define. The error bars in the data end up larger than the effect you're trying to measure.

Second: The muzzle velocity difference between a round baked in a hot chamber and a round not baked in a hot chamber is absolutely meaningless to a ballistics calculation outside of really seriously extreme circumstances of silly long range and silly small target size and silly large case capacity. Before wasting a single moment of thought on this, figure out the maximum change to your trajectory and compare that to your target size. If the maximum velocity difference you can obtain experimentally is insufficient to exceed your target size then your target size is greater than your danger space and any measurement along these lines is a complete waste of effort. If the drop delta is larger than your target size then you need to get closer by definition.

If you wanted to measure such a thing directly then you simply want to do something that's essentially pointless. When you get up to huge cases like .338lap and the cheytacs and BMG based stuff then the powder capacity is so huge that you can, under pretty extreme conditions, see deltas in velocity that are important enough to bother wondering about but by that time the distance has grown to something really properly silly. Pretty much if you're needing to worry about it, you're doing something objectively silly.
Other than maybe shooting 5 or more steel targets at say 1500 yards under what circumstances would you expect to shoot at something at long range with a hot barrel?
 

TennJed

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I have a practical application for this, trying to become very consistent at long range shooting. In the beginning at least for me, there are numerous variables to figure out, trigger pull, cheek weld, stock support, breathing, etc, etc. as well as coal, powder charge, etc. etc. When I go to the range, I have to shoot more than 5 rounds to practice or I'll be at least 200 years old before I learn to shoot. One of my rifles 308, has a lightweight barrel and it heats up considerably after 5-10 rounds. Being new, I am always wondering if I'm losing my ability to shoot or the slight expansion of the barrel diameter is affecting the groups. Once I learn how to shoot, I agree it's probably not that important. Thanks.
 

StanleyActual

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I have a practical application for this, trying to become very consistent at long range shooting. In the beginning at least for me, there are numerous variables to figure out, trigger pull, cheek weld, stock support, breathing, etc, etc. as well as coal, powder charge, etc. etc. When I go to the range, I have to shoot more than 5 rounds to practice or I'll be at least 200 years old before I learn to shoot. One of my rifles 308, has a lightweight barrel and it heats up considerably after 5-10 rounds. Being new, I am always wondering if I'm losing my ability to shoot or the slight expansion of the barrel diameter is affecting the groups. Once I learn how to shoot, I agree it's probably not that important. Thanks.

yep, those sporter contour barrels dont take much to heat up. Under 5rds ? Magnums are hearing up in my experience in 2-3 rds. I do know Lowlight mentioned one time that many of the guys in his Alaska PR classes show up with sporter vontour hunting rifles and he won’t let them take more than 3 shots at a time for that very reason Gotta let it cool

If you’re mindful of it, and don’t allow yourself to shoot when your barrels smoking, it won’t have any affect on you.
 

TennJed

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yep, those sporter contour barrels dont take much to heat up. Under 5rds ? Magnums are hearing up in my experience in 2-3 rds. I do know Lowlight mentioned one time that many of the guys in his Alaska PR classes show up with sporter vontour hunting rifles and he won’t let them take more than 3 shots at a time for that very reason Gotta let it cool

If you’re mindful of it, and don’t allow yourself to shoot when your barrels smoking, it won’t have any affect on you.
Thank you, I'm glad I'm not crazy
 

Professor Doolittle

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Again with the tyranny of the discontinuous thought process and this is compounded by the mental error of making a mountain out of an ant hill. Ughh. The short and sweet answer is, you're overthinking things. The long way is below.

First: Continuous non-linear processes like thermal conductivity through an irregularly shaped mass cannot be spot measured from one small place on that mass and then that measurement used to determine how some other continuous process will develop. This is why we use large sample sizes in experiments that seek to determine the kind of relationship you're wanting to define. The error bars in the data end up larger than the effect you're trying to measure.

Second: The muzzle velocity difference between a round baked in a hot chamber and a round not baked in a hot chamber is absolutely meaningless to a ballistics calculation outside of really seriously extreme circumstances of silly long range and silly small target size and silly large case capacity. Before wasting a single moment of thought on this, figure out the maximum change to your trajectory and compare that to your target size. If the maximum velocity difference you can obtain experimentally is insufficient to exceed your target size then your target size is greater than your danger space and any measurement along these lines is a complete waste of effort. If the drop delta is larger than your target size then you need to get closer by definition.

If you wanted to measure such a thing directly then you simply want to do something that's essentially pointless. When you get up to huge cases like .338lap and the cheytacs and BMG based stuff then the powder capacity is so huge that you can, under pretty extreme conditions, see deltas in velocity that are important enough to bother wondering about but by that time the distance has grown to something really properly silly. Pretty much if you're needing to worry about it, you're doing something objectively silly.
I’m trying to be accurate at 1500 yards with a 300 norma mag. And my ammo runs a standard deviation of 8.5fps for muzzle velocity around 3100fps mean. Using my ballistics app the difference between plus and minus one standard deviation alone is two clicks on the turret. You’re right that without understanding what that physical error means in inches I’m wasting my time and I don’t know what it is but I know that a couple clicks makes a difference quite often over 1000 yards.
 

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StanleyActual

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I’m trying to be accurate at 1500 yards with a 300 norma mag. And my ammo runs a standard deviation of 8.5fps for muzzle velocity around 3100fps mean. Using my ballistics app the difference between plus and minus one standard deviation alone is two clicks on the turret. You’re right that without understanding what that physical error means in inches I’m wasting my time and I don’t know what it is but I know that a couple clicks makes a difference quite often over 1000 yards.

don’t get your barrel hot.
So what’s the process? You gonna Have that temp gauge and your chrono out everytime your barrel gets hot so you can “try to predict” how that temp is gonna affect your velocity with every shot at close to a mile? Im Not seeing that being reproducibale on a shot to Shot basis. Beat bet is to just let it cool down, and go again.

I don’t think I’ve ever heard of anyone doing that. But maybe they are. What I have seen is guys putting one of them fans that blow air into the chamber to cool it in down ever so often to help cool the barrel down faster.
 
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Professor Doolittle

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don’t get your barrel hot.
So what’s the process? You gonna Have that temp gauge and your chrono out everytime your barrel gets hot so you can “try to predict” how that temp is gonna affect your velocity with every shot?

I don’t think I’ve ever heard of anyone doing that. But maybe they are. What I have seen is guys putting one of them fans that blow air into the chamber to cool it in down ever so often to help cool the barrel down faster.
No but I could characterize temperature versus change in muzzle velocity to support fine adjustment by educated guess in the field.
 

StanleyActual

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No but I could characterize temperature versus change in muzzle velocity to support fine adjustment by educated guess in the field.

hey you know what, whether you can actually “use it” in the field is kinda irrelevant. It would be something cool to play with to just see how much the temp does affect velocity. I like experimenting and messing with stuff like that.

iid Venture to say that one of them calibrated temp guns will be plenty good enough for what you’re trying to do. The variations in your muzzle velocity from shot to shot is gonna have a far greater impact than the few degrees difference in temp from the Chamber to the outside of that barrel.

Interested In what your come up with. Let us know how it turns out.
 

Muddyboots

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A Christmas Story comes to mind and suggest putting your tongue on barrel. If you leave skin, too hot. 🤣
Instead of measuring temps, best way to extend shooting of a specific rifle is to cool it down through air cooling pump assist which cools chamber and entire barrel down from inside out. Tons of LRH threads on this. It does work, but on hot day 80+, it will be slowwwwww process. Some cool air down through crushed ice water. I have used a pump to cool barrels for probably 25 years and I still bring other rifles to shoot while one is cooling. I try to get barrel down within 10 degrees of ambient temperature which has worked for me. If it is a belted magnum, short magnum, or other high capacity cases high velocity, it will heat up faster and take longer to cool down. Just a product of the firestorm you are putting down your barrel.

I understand it is nice to have "data" on how hot the barrel is versus velocity but why not just cool the barrel down? If only 5-10 shots it shouldn't take that long to cool down.
Is San Fran that bad?:eek:
 
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