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Cooling Hot Barrel/Gun


KevinB

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Been surfing around on this topic between chores most of the morning and can't find exactly what I'm looking for.

During practice sessions, my guns get really, really hot. Especially when shooting steel because of the lack of down time for pasting targets. I intend to hit the barrel with a thermometer at some point to exactly quantify it, but it won't be today.

Do any of the folks here with some metallurgy knowledge know if it would hurt anything to toss the gun/barrel in a bucket of water? I got the idea from a full-auto weapons demo where many of the rifles were suppressed, and the company rep locked the bolt to the rear and threw it in a shallow barrel of water after two or three magazines. The water would boil off the can to the point it the hot water would rise up through the barrel and spurt out of the chamber with some authority, telling me it was shedding significant heat. I asked him if that was rough on the equipment, and he said it wasn't and it could take that all day.

I'm not entirely convinced when using my own money that's a best practice.

In looking around, I've seen some advice that doesn't really answer the question asked. I've seen "I just bring a few different guns to the range and shoot some while others cool" and "I wouldn't do it, but I don't really know anything about metallurgy."

My intuition is that it will be fine, but that's all it is.

Anyone with actual knowledge have any ideas?

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Have to know the barrel material to look up heat treatment data...but I would guess that even shooting 1000 rounds as fast as possible, you still will not get to a tempering temperature, much less to phase change temperature (usually glowing red hot) where a quench would have the effect of hardening steel.

I like shooting a lot when I have access to a range with steel as well, but usually when my gun gets that hot it means I'm well into the diminishing returns of ammo use and practice efficiency. I just let it cool off while I load mags, paint some steel, and think of a drill that makes better use of my ammo.

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I use Titegroup in a stainless steel KKM barrel in Florida, and my barrel can heat up to "can't touch it with bare skin" in three or four magazines. I'm well aware of diminishing returns during practice and I don't hold myself to any particular round count.

According to the website I just found, it looks like KKM uses 416R stainless hardened to 45 Rockwell.

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As a tool & die maker for around 40 years, I can tell you it's not getting hot enough to bother the metal just from shooting. I heat treat tool steel all the time. You have to get anywhere from 1750 to 2100 degrees F for a phase change. You have to get to 350 or 400 minimum to draw back the hardness any. The most you might do with a few cycles of hot and cold is stress relieve the barrel. That would make it better, not worse. Make sure to use clean water, not anything with any acids or chemicals in it.

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From Machinery Handbook:

416 Hardened is RC43

400F Temper is RC41

600F Temper is RC39

800F Temper is RC41

1000F Temper is RC31

Annealing Starts at 1300F

But cooling at a rate faster than 25C/hour from annealing temperatures restores martensite (hardened) properties. You don't want that since it a fully hardened barrel will probably crack.

It sound silly, but you could smear a little vegetable oil on the barrel and if you see the gun smoking, you are at the smoke point of that oil. http://whatscookingamerica.net/Information/CookingOilTypes.htm

I'd be interested to know what temperature barrel makers temper their 416 barrels at.

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I use a small battery operated fan and while I load my mags, I turn it on and position it to blow down the barrel. I can feel the hot air coming out of the breech and the pistol cools off a lot faster than just sitting there.

I tried one of those fans with built-in water sprayer and it cooled even quicker but spraying water on a blued pistol just went against the grain...

Maxam fan

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  • 3 weeks later...

Aluminum and Copper are great at removing heat while welding to keep from melting things you didn't want to melt.

A piece of scrap aluminum can be had for very little to lay the pistol on and allow the heat to travel to it.

I have large pieces all over my work bench for heat control and it works great

also.... Thanks to all the guys for the metallurgy stuff and oil smoke temp. Good Stuff :cheers:

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I like the heat sink idea. Not every bay I shoot on has access to water, but I could throw a sheet of aluminum in the car and have it everywhere. How thick would you recommend as a minimum?

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Barrel mfg. are well aware of the heat produced by firing.

I doubt any of use could be able to fire enough rounds fast enough to bring temps. up to the point of degrading or changing the metalurgy.

You know the barrels hot after shooting, so stop touching it. :mellow:

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They are correct in that it is really hard to get a barrel hot enough doing what you are doing. A Pencil barrel on a M16 with low mass parts might get there and crack a gas tube, but not the barrel.

I have dunked barrels in water, used compressed air and other methods to cool barrels. Water with your lube might not be a good idea though.

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I like the heat sink idea. Not every bay I shoot on has access to water, but I could throw a sheet of aluminum in the car and have it everywhere. How thick would you recommend as a minimum?

I'd say about 1/2" thick and the same width and height as the gun. Obviously more is better for thermal mass, but then it will get to a size that's not fun to carry around.

I have a 12" x 8" x 3/4" piece that I keep in the bag to set down and work on the gun at the range also. There isn't always a great place to bang around on things at the range.

If good direct contact is made, aluminum and copper pull heat out much faster than water.

I'll PM you a link to a guy on ebay I buy scrap bits from at a good price

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I like the heat sink idea. Not every bay I shoot on has access to water, but I could throw a sheet of aluminum in the car and have it everywhere. How thick would you recommend as a minimum?

I'd say about 1/2" thick and the same width and height as the gun. Obviously more is better for thermal mass, but then it will get to a size that's not fun to carry around.

I have a 12" x 8" x 3/4" piece that I keep in the bag to set down and work on the gun at the range also. There isn't always a great place to bang around on things at the range.

If good direct contact is made, aluminum and copper pull heat out much faster than water.

I'll PM you a link to a guy on ebay I buy scrap bits from at a good price

How exactly do you get good contact between a block of aluminum and a round gun barrel?
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I like the heat sink idea. Not every bay I shoot on has access to water, but I could throw a sheet of aluminum in the car and have it everywhere. How thick would you recommend as a minimum?

I'd say about 1/2" thick and the same width and height as the gun. Obviously more is better for thermal mass, but then it will get to a size that's not fun to carry around.

I have a 12" x 8" x 3/4" piece that I keep in the bag to set down and work on the gun at the range also. There isn't always a great place to bang around on things at the range.

If good direct contact is made, aluminum and copper pull heat out much faster than water.

I'll PM you a link to a guy on ebay I buy scrap bits from at a good price

How exactly do you get good contact between a block of aluminum and a round gun barrel?

So if you were using a block of aluminum for the purpose of heat treating something, you would mill a spot in the aluminum that would fit the part perfectly.

It is common for knife makers to do this with two pieces of aluminum to sandwich the blade in. It removes heat very fast and creates a much more uniform treatment because there is less temp fluctuation like boiling water.

In the OPs case, he is just laying the gun on its side on the block of aluminum. I don't think it will be magical, but it will draw some temp out of the gun through the slide/frame contacting the aluminum.

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You also bring up a good point.

I bet the most optimal thing to do would be have a bunch of aluminum powder sewn into a bag or some sort of gun sock / cover.

Lay the gun down on the bag, or rap it around the slide when not in use and the head will make its way into the aluminum powder.

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They are correct in that it is really hard to get a barrel hot enough doing what you are doing. A Pencil barrel on a M16 with low mass parts might get there and crack a gas tube, but not the barrel.

I have dunked barrels in water, used compressed air and other methods to cool barrels. Water with your lube might not be a good idea though.

It's a Glock with slide glide on it. It can take a dunking!

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JP makes a nice barrel heat sink, but it is made for their barrel O.D. so you'd need to check to see if it would fit yours. I like mine, but others have said they don't either don't really do much given a typical round count in a match, or don't like the extra weight.

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If good direct contact is made, aluminum and copper pull heat out much faster than water.

Not even close!

+1!!!!

It seem incorrect but you can test this in your own kitchen. You should also not confuse the idea of "Rate of heat transfer" and "heat storage capacity"

Aluminum's thermal conductivity is over 350 times that of water, but water has 4.7 times more heat storage capacity.

http://koolance.com/cooling101-heat-transfer

When you use an aluminum/copper pan to heat water, the pan heats up VERY fast while the water heats up very slowly.

Water has an amazing heat storage capacity, but it takes a long time to get the heat in to the water as compared to copper or aluminum

Copper heats up VERY fast but it doesn't have a very good capacity for heat energy at all.

Aluminum heats up a bit slower than copper but has a much greater ability to store heat once transferred

Water in this comparison heats up very slow, but can store magnitudes more heat energy than the other two. (this is why evaporating sweat cools our skin so well)

Another thing to consider is that heat cannot transfer evenly through boiling water. The hot item you dunk in water creates the points where the water boils and turns into a gaseous state. Heat transfer will drastically diminish at the point where the item is surrounded by gas instead of water. Plenty of knife makers will use oil to heat treat their blades for a more uniform heat transfer as opposed to water. Think of it as having more control of the vapor layer which slows the heat transfer, and then when the process changes and the vapor layer breaks away, the direct contact to the fluid is more uniform (there are plenty other reasons to use oil instead of water or the other way around that you could debate for years)

Here is a great link of a company discussing quenching steel in oil. Lots or really cool science and graphs to reference.

The best snipet I found is this. "The ideal quenchant is one that exhibits little or no vapor stage" <--- you get no vapor stage from a direct contact metal quinch.

http://www.globalspec.com/learnmore/materials_chemicals_adhesives/industrial_oils_fluids/quenching_oils_heat_treatment_fluids

here is a piece from a college where they are setting up to test the heat capacity of copper, aluminum, and water if you'd like some other input.

http://www.haverford.edu/educ/knight-booklet/heattransfer.htm

Enjoy :cheers:

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I'm no metallurgical expert but that's all pretty interesting. However, the ability to get 100% surface contact with both the exterior and INTERIOR of the barrel has to give some water some advantage here, despite its less than perfect thermal properties. Just my thoughts...

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JigSaw, you are missing several key points, two of which is the energy it takes for phase change as well as convection. I did graduate level coursework in Heat Transfer, but the real world applications don't hold variables fixed so you can solve the problems in the academic world. The OP did not ask about heat treatment, which is what you are answering, but how to cool. Water is the fastest and most effective method to cool down a heated barrel. Cheap and easy. Not complex based on academic exercises.

You have learned just enough about Heat Transfer to entice you to ignore real world applications and tests. The bane of many engineers is also why we are losing our engineering edge to other countries. That and "value engineering."

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