[Question] Barrel Cooling Techniques

[TITAN308]

Ok so I have some more questions after researching some other methods that bench rest shooters use that we can employee in our project.

Looks like some of them have taken a liking to all kinds of homemade methods, but one in particular that caught my interest was a short blast of CO2 to the barrel. Now the first thought is, won't that damage the barrel? Science tells us heating and cooling to quickly causes stress to the metal and microscopic cracks, fissures, etc etc can occur and make the material become brittle.

However, it would appear most people shooting bench are not getting the barrel temps nearly high enough for this type of reaction to occur. Its one thing to drastically drop the temp on a barrel that has had a hundred rounds from a beta mag dumped through it vs. someone who fires 5-10 shots.

Can anyone comment further on the science of this?

I was thinking C02 cartridges are readily available at local retail stores for very cheap ($6 per 15 on average) and I could rig a mounting and puncture system with some tubes to basically inject the C02 inside the shroud and onto the barrel.

...or taking the system as far as a thin jacket for the barrel and the C02 is injected into a hollow space between the jacket and barrel.

I have a lot of available space on the shroud, so mounting has all kinds of options (think shotgun shell holders, but for C02 cartridges and a puncture system operates by a twisting knob on the bottom of each that pushes it up into a nipple, the nipple is hooked to a tube, the tube sends the C02 to its destination.

Thanks for any edumikation you can provide me.

 

[Driftertank]

If it were me, and given the size and weight of the project i've seen, i'd think of possibly recirculative liquid cooling. Moving water-based coolants have rather high latent heat-transfer properties, and flow will help distribute thermal energy so your barrel would maintain more uniform temperatures along its length, without the risk of shock-cooling and the attendant metal-fatigue issues. The trade-off would be weight and complexity, as well as the need for an external power source.

That's how it looks in my head anyway. Could be, i know just enough to make myself sound stupid.

 

[TITAN308]

We need to to find a happy medium with a system that is low maintenance, cheap to 'recharge', and in general does not require much input from the average user.

We had considered a close looped system with a 9-VOLT operated heat exchange, but the cost and complexity is simply going to be to much to keep it open to a bigger audience.

If we can get some confirmation that barrel temps are far below the threshold for these elements to occur then we can make an affordable and rechargeable system that simply requires the user to activate and replace compact CO2 canisters. We can even go as far as developing the system to limit the flow even if a CO2 canister is fully punctured very quickly.

I envision a system of tubing that will dispense the C02 at all angles over the entire length of the barrel.

Our other method of cooling is developing exactly what JP Rifles has done (barrel length heat sinks), but for non-contoured (bull barrel) and industry standard contoured rifles. Currently JP Rifles only develops heat sinks specific to their own barrels.

We have thought long term that a heat sink with a thin hollow layer could have the CO2 injected directly. However currently we are looking at a more simple "extinguisher" type system.

 

[shuvelrider]

Post a picture of this "Project Titan", your website is down. Is this a bench rifle only ? I would think a nitrogen filled coil/jacket around the barrel could work, have a valve for re-charge as needed.

 

[adelbridge]

go to a bike shop and you can buy a CO2 inflater and cartridges for $15-20, rig up a hose and let us know how it works. With the price of ammo these days I relax and take my time. 1 shot a minute and your barrel shouldnt get hot enough to cause stringing.

 

[451 Detonics]

I realize it may irritate some but I feel creating a heat sink around the barrel would be an efficient way to cool it and that seems to be the biggest purpose of the Straight Jacket system from Teludyne. I know there was a lot of talk on here about it and some very good testing done.

Might be worth considering...

 

[ISO1600]

I dont know much about the pure science of it all, but i'd tend to agree that a simple heat sink would probably be the most reasonable means to achieve this.

 

[TITAN308]

Our standard method of cooling already utilizes a full barrel length heat sink. It is identical for the most part to JP Enterprises's (jprifles.com) setup, but since their heat sinks are specific to their in-house barrels we needed to make some for bull barrels and standard contour barrels.

We want an addition "option" of an on-demand cooling system.

Check back to the website later tonight if you want pics of the project, the website is basically under construction while I get its final design/layout in place.

 

[Rail Driver]

Have you considered something much more simple than your CO2 idea - mount a few small battery powered or even solar powered fans in the rear or along the length of the shroud, retaining the heatsink. Increasing airflow over the heatsink will increase it's efficiency very noticeably - If you're looking into cooling systems I strongly suggest studying active and passive cooling solutions for computers - they're small, lightweight, self contained, and much more effective and easy to use than any CO2 system you could devise not to mention MUCH cheaper to produce.

 

[TITAN308]

We have a few PC cooling systems we are looking at.

At this stage of the game we are just gathering ideas to see what is the most balanced between cost effective, maintenance and repair friendly, and of course useful.

 

[PercyShelley]

In WWII there were various experimental tank cannons that were rigged to squirt compressed air down the bore after every shot to clear out the fumes. I want to say that the KwK 43 8.8 cm L/71 actually had this, but I can't find a diagram to say for sure.

So, the idea was constructed and demonstrated at larger scales at least.

 

[jmr40]

It can get pretty hot here in the summer. 100+ is not uncommon at the range. When it is that hot it takes a very long time for a barrel to get cool enough for meaningful load develpoment or practice. I usually do any work where a lot of shooting is required at cooler times of the year, but sometimes you gotta do what you gotta do.

I always take several guns with me to the range including at least one .22 for plinking while my centerfire barrels cool. When it is really hot I just leave the truck running with the AC on high and leave the rifles in the front seat. I get them out 1 at a time. As soon as I fnish firing a group with one rifle it goes back in the truck and another comes out.

Not very Hi-tech, but it works better than any other system I've tried.

 

[Elkins45]

Sorry if I'm late to the party, but why not a plain old water jacket?

 

[ApacheCoTodd]

Have you looked at the "Lewis Gun's" passive cooling jacket? It was eventually found to be of questionable benefit both on and off aircraft but is an interesting starting point for a "bench shooting" - as in "bench racing" - conversation.

 

[-v-]

To bounce of ApacheCoTodd, perhaps look at what the Russians are doing with their Pecheng MG. Basically the same Lewis gun cooling system, but smaller and a little better tuned to get meaningful airflow over the barrel and cooling veins.

Also, what about an adapter to connect to a small paintball CO2 tank? Alternatively have a system that sprays a CO2/water mix over the barrel, have it rigged up like a paint sprayer where moving CO2 draws water into the stream to spray the barrel with both cold CO2 and water to aid in cooling?

I guess the biggest question is what do you consider the reasonable maximal rate of fire for your rifle?

 

[Jim Watson]

Sounds like somebody has been reading too much Hammer's Slammers with nitrogen cooling of power guns.

There was a prairie dog rifle with circulation cooling system some years ago. Big and bulky, it was meant for a lot of shooting from one location. Kind of like a water cooled MG.

I don't know how much actual cooling you would get from a CO2 cartridge as used in pellet guns. Somebody with the text and reference books I lost in The Incident could probably figure it out for you.

 

[Nuclear]

If you just want consistent conditions shot to shot, you could heat the barrel to its normal operating temperatures ;-)

How about a portable version of those misting systems that businesses use in hot weather? One could be rigged along the barrel, constantly misting it. All you would need is a faucet and hose connection. Or a water source and a pressurization device, like a compressed air tank. But a more practical system would probably just be blowing air over or down the exterior of the barrel. And fins on a barrel do work as a passive system if you have fluid flow over them.

 

[DHass]

Jeez, can we get more complicated here.

Just wrap paper towel around the barrel and wet it down with water once and a while. There's your full coverage, hydro-oxy gas heat displacer.

I know now you will whine about rust. Well the barrel is warm so what moisture is on there will evaporate.

 

[TITAN308]

DHass I think you are missing the point.

The application in question does not allow for direct access to the barrel. It is encased in a full length shroud.

And to be honest, selling tactical towels doesn't seem to have a large following in the market.

(Edit: Maybe I could make a "SHAM-WOW!" knock off called the "SHAM-POW!" lol)

 

[bfoosh006]

One of these ,http://www.amazon.com/Coleman-4D-Universal-Quick-Pump/dp/B00005JD3Z with a piece of tubing that fits in the breach. Works pretty good !

 

[Andrew Wyatt]

A liquid cooling system using liquid ammonia would work better than one with water.

you can actively cool the ammonia with any number of cryogenic gasses, since it only becomes solid at -110F.

 

[Andrew Wyatt]

you could size the radiator to replace the lid of a standard dewar flask, thereby simplifying the customer's logistics for their cryogenic liquids.

 

[Fremmer]

Drum filled with water, add ice, dunk rifle barrel.

(Jk)

 

[crossrhodes]

Purpose?

What's the intended use/purpose of the rifle? Bench, tacticool (no pun intended) or just R&D to see what sticks. Cool looking rifle!.

 

[lsmith79]

Barrel Cooling

I saw a guy at SHOT demonstrate an amazing barrel cooling system that he had developed. It blew industry people away. No one could figure out his secret. I think he is an engineer/gunsmith, and had obviously done a lot of R&D on it. He had data on M249 field tests he had conducted. Incredible! You might want to contact him, he is/was looking for a partner to integrate his system (could be a match). I will look for his business card.