how do you measure barrel temperature in a reliable manner?

StanleyActual

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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:

agreed easier to focus on not getting it that hot in the 1st place
 

Professor Doolittle

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agreed easier to focus on not getting it that hot in the 1st place
Well I should have put more background into my initial post. The whole issue started with load ladder development, that in the process of shooting 60 rounds the barrel temp is climbing. I've read that pros will shoot five to ten rounds then come back to a cooled state but they never describe how they satisfy what it means to return to the original state. My sh(t show cost me $3K because first I paid $300 for a load ladder which I shot and ordered the load from my best group which was .36MOA on five shots. Spent $2700 on 500 rounds with that recipe, only the day I receive it discovered the muzzle brake had been loose while I shot the load ladder. To top that off we shot with both labradar and magnetospeed mounted via chassis with the new rounds only to discover the muzzle velocity of everything, new bullets and old control groups, had increased by 40fps because the barrel had not finished breaking in, I only had around 150 rounds out of it when I ordered the reloads. So what do I have? Barrel temperature shifting muzzle velocity, barrel wear shifting muzzle velocity. I'm ready to buy applied ballistics software package for $200. Like the gentleman said before, if you don't know what error you're chasing don't f*(k with it. The only good news is the reloads are shooting at a standard deviation of 8.5fps, that's smoking good. Berger bullets stock was very close to that, though, 10.2fps. Berger seems to be an amazing company.
 

Professor Doolittle

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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.
I spray atomized water from a bottle on the barrel to cool it quicker, plus a chamber fan. My problem is more about how do you know you are at the defined starting temperature again? I see a lot of evidence that the muzzle velocity moves with barrel temperature so I want to nail down what's happening. Everything else about my shoot is precise, consistent, or irrelevant. But that barrel temp means something and I don't know how to control that variable.

 

Muddyboots

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Maybe this will get you the "data" that you want to see. Assume the muzzle is an exhaust vent. You can measure the exhaust temperature of the barrel by using a pump. The baseline temp is before you shoot. You could measure each shot if wanted and graph temp rise against ambient. Use pump to return exhaust temp to baseline.

Edit added: timed intervals between shots for better QC control as well.
 

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
Curious why you would bring up this second issue, how long the round bakes in the chamber before its fired. My instructor has me not chamber the round until everything is otherwise ready to go. I was taking the barrel temperature effect to be different from the cartridge heating effect. Which did you mean?

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.
 

nealm66

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Well I should have put more background into my initial post. The whole issue started with load ladder development, that in the process of shooting 60 rounds the barrel temp is climbing. I've read that pros will shoot five to ten rounds then come back to a cooled state but they never describe how they satisfy what it means to return to the original state. My sh(t show cost me $3K because first I paid $300 for a load ladder which I shot and ordered the load from my best group which was .36MOA on five shots. Spent $2700 on 500 rounds with that recipe, only the day I receive it discovered the muzzle brake had been loose while I shot the load ladder. To top that off we shot with both labradar and magnetospeed mounted via chassis with the new rounds only to discover the muzzle velocity of everything, new bullets and old control groups, had increased by 40fps because the barrel had not finished breaking in, I only had around 150 rounds out of it when I ordered the reloads. So what do I have? Barrel temperature shifting muzzle velocity, barrel wear shifting muzzle velocity. I'm ready to buy applied ballistics software package for $200. Like the gentleman said before, if you don't know what error you're chasing don't f*(k with it. The only good news is the reloads are shooting at a standard deviation of 8.5fps, that's smoking good. Berger bullets stock was very close to that, though, 10.2fps. Berger seems to be an amazing company.
Wow that seems crazy $ to me although if I added my time into the equation it would probably be cheaper to pay to have it done. Is the ladder done with fire formed brass?
 

nealm66

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Hmm, well, if you didn’t send 60 pieces of brass that you shot from your rifle, it wasn’t. It can group a little different and also have slightly different velocity even thou seating depth and powder charge is the same. Not always. Some new brass comes pretty close to your chamber and neck isn’t ridiculously tight but most times it needs fire formed to give an accurate ladder
 

antelopedundee

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Seems to me you could try a thermocouple that is a solid rod as long as the rifled portion of the barrel and just undersized enough to fit into the bore so a .308 maybe a .300 or a scosch less in diameter.
 

Professor Doolittle

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Hmm, well, if you didn’t send 60 pieces of brass that you shot from your rifle, it wasn’t. It can group a little different and also have slightly different velocity even thou seating depth and powder charge is the same. Not always. Some new brass comes pretty close to your chamber and neck isn’t ridiculously tight but most times it needs fire formed to give an accurate ladder
That's interesting. I never heard of fire forming. It was new Lapua brass.
 
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