Barrel cooling times

[Chris Edmondson]

Decided to compare a couple of forced-air barrel cooling methods.

I used a self-adhesive thermocouple sensor adhered to the left side of the chamber, this is a K-Type sensor with sufficient accuracy for the task at hand, the sensor was connected through an interface to a laptop PC, readings were logged each second over a two hour shooting session :



The forced-air cooling methods were a USB-powered chamber fan, and a Ryobi clip-on jobsite fan:



The control was to let the barrel cool naturally, then the chamber fan, then the jobsite fan, then both fans. I selected a high temperature and low temperature common to all methods; in other words, they all start at the same-ish high temp and cool to the same-ish low temp, within 1/2 a degree.

The results shown below indicate the barrel took about 30 minutes to cool naturally, 19 minutes with the chamber fan, 10 minutes with the jobsite fan, and 8.5 minutes with both fans:



More useless fun caused by being retired, lol.

 

[Fast14riot]

Its actually pretty good to know this, unfortunately the external fan is limited in use, many ranges and matches rifles must be off the line and do not have benches or gun racks to set them up. But good data anyway!

 

[choprzrul]

Using chamber chiller + external fan, I can do load development ladders with 90 second shot intervals and maintain a barrel that's just barely warm to the touch. Granted, it's usually 60-65 degrees here on the coast where I shoot, so that helps also.

 

[Syncrowave]

Cool inquiry, thanks for posting your findings. It'd be interesting to see what you got on a Cr-Mo barrel with identical contour, compared to SS, since (IINM) 4140 is close to twice as thermally conductive as 416R.

If you wanted to go really crazy with multiple variables, it'd be interesting to see how average group sizes changed at all different points in the heating and cooling cycles, since presumably a SS barrel, with less thermal conductivity, would be more prone to moving with changes in temperature, compared to CrMo, assuming they have similar levels of stress relieving...SS is notoriously tricky to weld for this reason; because the heat (and consequent expansion) "piles up" locally much more than with regular steel, SS tends to move and distort much more when it's welded, and not just because metal shrinks and "pulls" when it freezes. But to do such a study justice, I suspect you would need to measure bore temperature and surface temperature to somehow quantify the differential...gonna need a compass, theodolite and some other land surveying equipment for this rabbit warren!

 

[charlie b]

You could use a laser in the muzzle. Corner reflector at range and a camera receiver. Would take close fitting mandrel in the muzzle to get repeatable measurements. The laser could be secured to the muzzle, but, that would change the node and mess up accuracy results.

 

[gmr4]

Maybe some people will read this and change there evils ways.. you know.. the dang huge mosquito sounding things stuck in the chamber that kill everyones buzz.

 

[Chris Edmondson]

A fellow shooter at our range who usually has two or more rifles to shoot gets good service from chamber coolers. doesn't matter if it takes longer to cool since the rifle is sitting on the back bench anyway.

I prefer the jobsite fan, the battery lasts for many range sessions, and it's dead quiet. The range is OK with hanging the chamber flag over the scope turret as long as the other required safeties are engaged; bolt open, magazine removed. Even if the flag was required I really don't think much air gets into the chamber anyway with the jobsite fan.

Anyway, now that I have the gadget working correctly I'll probably fiddle around with group barrel temps and group metrics, always need a good rabbit hole I say .

 

[gmr4]

Its actually pretty good to know this, unfortunately the external fan is limited in use, many ranges and matches rifles must be off the line and do not have benches or gun racks to set them up. But good data anyway!

So where do the guns go? I’ve put mine in the back of the truck and run the fan, I’ve used the fan in the back of a Toyota hatchback.. I’ve tilted the fun almost straight up and blown on a gun in a rack…..

 

[ELR LVR]

Maybe some people will read this and change there evils ways.. you know.. the dang huge mosquito sounding things stuck in the chamber that kill everyones buzz.

True that
I'm for the jobsite fan

 

[Fast14riot]

So where do the guns go? I’ve put mine in the back of the truck and run the fan, I’ve used the fan in the back of a Toyota hatchback.. I’ve tilted the fun almost straight up and blown on a gun in a rack…..

Back into the case, behind the firing line

 

[vonb]

That's good information.

I was doing load development at deer camp in the dead of summer; 90 degrees and 80%+ humidity. After a shot, I'd run inside and put the barrel in front of the window A/C unit. It would cool it down quick. So much so that my velocities were all over the place. That's where I discovered that cooling it down that was was creating some condensation. Ambient temps are where I want my barrels to be....That's tough to get to on a hot/humid day.

 

[moondog]

In the summer here, I bring a cooler with ice and water. Soak a small towel and wring out. Wrap it over the barrel. Repeat a couple of times. 2- 3 minutes it's back to shooting temp. I do it on the suppressor too if I'm running one.

 

[JackWolfKnives]

Where did you place the job site fan in relation to the barrel? Thanks for the data!

 

[Chris Edmondson]

Where did you place the job site fan in relation to the barrel? Thanks for the data!

When testing the jobsite fan only, it's placed on the right side of the rifle adjacent to the fully opened bolt, it roughly faces towards the barrel's muzzle so the airflow is into the chamber and along the barrel lengthwise.

When testing the jobsite + the chamber fans, the jobsite fan is on the left side of the action, facing towards the muzzle so the airflow is along the barrel lengthwise.

I should've snapped a couple pics .

 

[LVLAaron]

I switched to a dewalt jobsite fan... It's just a great thing to own, in general.

Also... I don't like those little shitbirds that blow dirty air through the barrel.

 

[D Coots]

How about a test using a wet towel from a beer cooler?

Works well when PD hunting. Easy to carry.