Barrel heating and cooling

[Boisblancboy]

1. Does anyone have any info on whether a 5 groove vs. a 3 groove would hear up more during a string because of more friction?

2. My Dad and I have gone in together building a FTR gun and are going to share it at matches. My question is how would you recommend cooling the barrel down between shooters? I figured we could wrap a wet/damp towel around it or something along those lines.

 

[Keith Glasscock]

1. Got both, they are the same.

2. Wow, that is a good question. Cooling a heavy barrel is not an easy task. They hold a lot of mass (and thus heat).

Let me suggest a couple of things:

First, let's look for a powder that has less heat. For example, Varget and N550 are about the worst (only behind H4895) for making the barrel hot. Some of the VV N100 series powders are much cooler burning, but don't always give the performance in terms of velocity. This will take some experimentation to determine and will severely complicate load development.

Second, same idea, try to shoot so as to maximize the time between shots so the barrel never really gets hot to begin with. This will reduce the amount of heat you have to get rid of in a hurry, and maximize barrel life.

Last, you'll need to be inventive in your cooling. In addition to the cool, wet towel (keep moving it around so it always has a cool part touching the barrel), find a way to pump air through the barrel (I used to use a hose that fit the OD of the barrel hooked to a battery operated air pump for blowing up inflatable boats)-just remember to keep the empty chamber indicator inserted. The real danger is in accidentally blowing dusty air into the barrel. You'll need to fashion a filter for the blower inlet.

Your plan is doable IMO, but you will have to pay attention to getting the barrel cooled down as quickly as possible after a string.

Good luck,
Keith

 

[Boisblancboy]

Thanks Keith. I would think with the combination of a wet towel and an air pump or direct fan would do wonders. A fan even blowing on the towel would help keep the towel colder.

Keep the ideas coming. Im just curious to hear the ideas.

 

[Heavies]

A bud I know that shoots with me put a wet towel on the barrel when he is shooting the string. His scores are pretty good so I guess it doesn't hurt anything.
If anything it keeps the mirage from the hot barrel down.

 

[CPorter]

We made some Terrycloth wraps with Velcro to hold it tight. Using polyacrymide (sp) Crystals found in gel neck coolers might add cooling capacity. Some people circulate water through the bore then run a couple patches before the relay starts.

 

[Boisblancboy]

I just thought of using a piece of PVC tubing that I could use as a sleeve over the barrel and blow air around It. Without explaining the minor details it would push air around and through it using a high volume blower.

 

[MrMajestic]

Instead of using that CO2 bottle and regulator to pump your Beer run the regulated side from the Tap into your chamber. Regulate to a couple PSI and you will be back to ambient in no time! Only issue is you would have to have a spare tank or buy bottled beer. ;D

 

[Boisblancboy]

Instead of using that CO2 bottle and regulator to pump your Beer run the regulated side from the Tap into your chamber. Regulate to a couple PSI and you will be back to ambient in no time! Only issue is you would have to have a spare tank or buy bottled beer. ;D

Do you think them chamber would have to be pressurised or just free flowing through it?

 

[MrMajestic]

It would have to pass through to remove the heat. Only a couple of psi or your tank won't last very long.

 

[Boisblancboy]

Yeah ok I got ya. For some reason I was thinking restricting the flow through the chamber to build pressure.

 

[Hombre0321]

Boisblancboy, The heating of a barrel in shooting F-Class is just going to be something you have to deal with. There is no way to slow down your rate of fire to a point that you could even begin to help the barrel from getting hot. besides if you do try and do that you better be the best at wind reading there is.

I do not believe that there is enough difference "If Any" between the friction of a 3 groove vs 5 groove rifling to make any difference at all. Could be I guess but I doubt it. You also need a load that works well in your rifle and is accurate. If in finding that load it happens to be a powder that helps keep your barrel cool please pass that information along to all of us, heck you could probably sell information like that.

I did see a contraption at a shoot not to long ago. This guy had a little pump, that pumped " He Said" kerosene down the barrel. The barrel sat in a container muzzle down, the pump was submerged in the kerosene in the container. He had the barrel at about a 45% angle on a rack muzzle down. The little pump, pumped from the container to the breach and slowly ran down the barrel into the container to be recirculated back to the breach and so on. It was one of those crazy Rube Goldberg kinda looking thing. Did it work? I don't know really but the guy finished way down on the list like in 35th spot or something. If it did work he should have been real glad he was using it or maybbe he would have finished last.

Roland

 

[DBailey]

Damp towel, not wet. You don't want water getting under the bedding. Stand the rifle muzzle up with the bolt open while you are applying the damp towel and it will cool to an acceptable level in very little time.

 

[Robert]

Boisblancboy, The heating of a barrel in shooting F-Class is just going to be something you have to deal with. There is no way to slow down your rate of fire to a point that you could even begin to help the barrel from getting hot. besides if you do try and do that you better be the best at wind reading there is.

I do not believe that there is enough difference "If Any" between the friction of a 3 groove vs 5 groove rifling to make any difference at all. Could be I guess but I doubt it. You also need a load that works well in your rifle and is accurate. If in finding that load it happens to be a powder that helps keep your barrel cool please pass that information along to all of us, heck you could probably sell information like that.

I did see a contraption at a shoot not to long ago. This guy had a little pump, that pumped " He Said" kerosene down the barrel. The barrel sat in a container muzzle down, the pump was submerged in the kerosene in the container. He had the barrel at about a 45% angle on a rack muzzle down. The little pump, pumped from the container to the breach and slowly ran down the barrel into the container to be recirculated back to the breach and so on. It was one of those crazy Rube Goldberg kinda looking thing. Did it work? I don't know really but the guy finished way down on the list like in 35th spot or something. If it did work he should have been real glad he was using it or maybbe he would have finished last.

Roland

Roland,

+1 on your comments..

One element I would add to the discussion with no comments is the thermal cpnductivity of different steels:

416 = 25W/m-k
CrMo (4140) = 43W/m-k

R.G.C

 

[johnu]

Heat will be transferred from the barrel most quickly via radiation, evaporation or conduction - a lot faster than blowing air through the barrel (convection.) If you can cool the outside of the barrel, heat will flow from the inside, and the outside has a lot more surface area. Evaporative cooling will be fastest, but you want to use a thin cloth - the objective is have the water in the cloth be evaporated off. A lot of energy (heat) is removed by that phase change.

John

 

[4xforfun]

I always just went a few feet to the car/truck and turned the AC on MAX and reved up the engine a bit. I closed all of the vents but one (or two if they are right next to each other) and let them blow down the inside/outside of the bbl. Leave the bolt out of the gun and let the cold air pas over/through the tube. A couple of min and you are good to go.

PS...Gas is WAy cheaper than new bbls and gunsmiths!!

 

[Boisblancboy]

Awesome guys thanks for the ideas! I'm sure I'll be testing a few of them to so which works the best for me.

Has anyone used one of the infra red laser thermometers to see what temps their barrels are reaching at the end of a string?

 

[Boisblancboy]

I should have said this project would be for a tube gun.

 

[johnu]

Awesome guys thanks for the ideas! I'm sure I'll be testing a few of them to so which works the best for me.

Has anyone used one of the infra red laser thermometers to see what temps their barrels are reaching at the end of a string?

I'd use one of those stick-on reversible temperature strips - I've seen some that go up to 90C. Might be some that go higher.
Advantage of them over an IR thermometer is that you can monitor temps by just looking at the strip.

John

 

[CanusLatransSnpr]

Another idea would be to buy acetone in the quart cans and apply a little to rag and wipe downt he outside of the barrel. Take care as not to get any on the finish of the stock or any of the bedding! When grass dragging snowmobiles we would scuff the clutches with 3m pads and then clean them with acetone between runs. Between a leaf blower and the evaporative cooling from the acetone, the clutches would be cool to the touch in no time! However, this is aluminum we're talking about. Not steel!

Mike

 

[jo191145]

If you can get W-748 to work in whatever cartridge you choose start there!
It is simply the coolest burning powder I know.