Cooling a barrel with a wet rag

[Uncle Mike]

Well, I worked as a welder in a steel fabrication plant...we used to put 'camber' in pipe, beams and channels with a torch and water hose.

With the pipe, we would heat the entire circumference of the pipe along the area to be arched, and then on the concave desired side of the pipe we would spray water onto the pipe.

This will make the prettiest bend... so I wouldn't cool one side of my hot barrel.

 

[falldowngoboom]

Thanks for breaking it down for me 1858. I was on the fence with the anecdotal info, but now I'll stick with standing my gun upright with the bolt open plus a small fan. Looks like I've got yet one more accessory to buy.

 

[MCMXI]

What are your thoughts on pouring water down the bbl? I wouldn't do it, but am not sure what damage would occur if any.

Mav, I wouldn't do it either but maybe not for the reason you mentioned. My concern would be rapid cooling and uneven internal stresses. Cavitation erosion occurs when water vapor bubbles collapse and it requires a significant pressure gradient in order to occur. I remember that it was/is a big problem in the cooling jackets of engines in over-the-road deisel trucks. The vibration of the cylinder linings provides the necessary pressure gradient but I'm not sure as to what pressure gradients would be established by pouring cold water in a hot barrel, say 300°F.

Barrels at rest have internal stresses since they deflect (sag) under their own weight. The examples in my earlier post are extreme cases and probably not representative of real-world conditions but who knows. The gun smith that I use (and shoot with) has been shooting for many years and is very knowledgeable. He hangs a wet towel over his barrel between stages but then again, he can always make a new barrel for next to nothing. I don't have that luxury so I may be overly cautious.

 

[ants]

Doesn't answer the question, but good data:

I once dumped a whole 20 round magazine rapid fire (about 10 seconds) through an AR-15, then immediately inserted a pyrometer probe into into the bore from both ends. Breach end (past the chamber) was 178 Fahrenheit, muzzle end was 158 Fahrenheit. I then used an infrared pyrometer and verified the same temp.

I did the same with a 1911 pistol, it was 10 degrees cooler than the rifle.

Of course, both felt HOT to the touch, but that's just a qualitative measure.

I didn't test it, but a large bore centerfire rifle might be around 200 degrees after 30 rounds slow fire. Or slightly above boiling (like 1858 found in his post above) in extreme cases.

I'm not drawing conclusions, just passing along the info.

.

 

[Offfhand]

Barrel Cooling

Nothing complicated about cooling a hot barrel. Here is a pix of the Winter Breeze system I use. I simply insert probe in chamber and open valve for a few seconds then back to shooting in about a minute. Since cooling is from inside the effect is even. The larger tank in background lasts for a week of high volume prairie dog shooting with several rifles. Get refills at welding supply shops.

Shoot well, safely and often....
Offfhand

 

[MCMXI]

but a large bore centerfire rifle might be around 200 degrees after 30 rounds slow fire. Or slightly above boiling (like 1858 found in his post above) in extreme cases.

Just to be clear, for the examples I presented, I simply took the number that SlamFire1 mentioned in post #7 and assumed he meant °F. I've never measured the temperature of any part of any firearm so keep that in mind.

 

[MCMXI]

Offfhand, the OP specifically asked about using a wet cloth/rag for cooling but regardless, that's an interesting system you have there. Can I ask you why you cool the barrel? Do you do it to reduce mirage, for accuracy, longevity or both, or neither? Are you at all concerned by the higher rate of thermal cycling that results from heating/cooling rapidly compared to the barrel heating up, staying hot for the duration then cooling down. Have you taken any before/after temperature measurements? I'm not fishing here or being a wisea$$, I am genuinely interested in why you cool your barrel and what sort of temperature differences you see in the field.

Thanks.

 

[Maverick223]

1858, I was referring to a different form of cavitation (same phenomena, different circumstances), where water is heated to form water vapor, and the cooled rapidly (buy the water flowing in from the top of the bbl) and collapses the bubble of steam. I have no doubt that there would be insufficient pressure to cause the form of cavitation which is typical in a pipe network, particularly within pumps and areas of higher pressure. Furthermore, I am not saying that it would occur...just that it seems plausible to me.