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Discussion in 'Long Range Hunting & Shooting' started by Orange Dust, Aug 12, 2019.
We'll agree to disagree.
We are all worried about shock, thermal cycling, and a host of other things. Getting a barrel too hot will ruin it quickly. In summer, it can take an hour for a carbon barrel to cool after just shooting it three times with a hot cartridge. This really makes for a long day. A method is needed to cool it in a reasonable time, or its not worth having IMO. None of the methods reported here cool the barrel back down anywhere near the rate that it heats up. They are also all reported to work fine. Has anyone ever gone overboard and ruined a barrel cooling it? Would love to hear how. I've learned a lot from this thread. I don't think any method shared here would be as bad for the barrel as continuing to shoot it hot and elevating the temp in the bore even more, or am I missing something? As for carbon, I haven't seen any method that cools from the inside that would change the temp faster than shooting it, so I'm going to disagree with the thermal shock theory.
Exactly.....air is not quenching a barrel.
Now, back to watching ZenA heat up his barrel really quickly !!
Yes, I am thinking you would have to use a liquid in the bore to make that happen.
here is some info on 416R ss barrel blank material i found online:
*950-1000 deg for 2-4 hours then air cool is used to stress relieve the steel
*re-anneal is 1300 degrees
*harden: pre-heat to 1400 deg, then austenitize at 1800 degrees for 30-60 min, then oil or salt bath cool/quench to below 125 degrees
* tempering starts at 350 to 450 degrees, but they recommend 500-900 degrees for 4 hours
The above is for a one time thing. I'm talking about cumulative effects.
Ambient air is fine, CO2 that has *just* made the phase change from liquid to gas will freeze off the regulator in moderately cold temperatures. BT, DT in the middle of the Baja 1000. It warrants taking care even in hot temperatures, maybe even particularly in hot temperatures to not cool too fast.
OTOH, it's your barrel, do whatever the heck you want.
The big difference is the way he's using the CO2. I could see the concern if it was liquid but he's using in a gas state which realy isn't cold, it's cool.
Depending on how hot the amint air is, I bet it's not lower than 60F.
Due to the flow and heat transfer "hot to cold" it's acting like a mini air conditioner.
If he flipped the bottle and liquid was ran through it, he could over harden it causing it to become brittle. Just like heat treating stainless steel knives and giving the a soak in liquid nitrogen before they fully air harden at ambient temp.
Out here in the desert with no ranges, we all keep our trucks running with the ac going to throw our rifles in to cool down for load development.
Some of these guy have made jigs to run the ac air straight in the chamber. So with an average of a 22 degree split of inlet and outlet air, there shooting 52f air wich is colder than the co2 gas shooting out the top of his bottle.
I use a CO2 setup like his to blast out Air conditioning coils all the time. Comes out just as cold as what comes out of my air compressor.
If I was going to use this method, I would think about using dry nitrogen over CO2. CO2 pipelines get moisture content build up. Dry nitrogen absorbs moisture and removes it.
But that's all just my opinion being universal certified in gasses and a knife maker for 30 years.
The conversion is actually in the bottle when it standing upright due to ambient air temp. You can take one bottle and put it in ice and the other at ambient hooked together and the majority of the co2 will migrate to the bottle in ice.
Frozen regulators are due to the following:
Heavy flow with pressure change.
Ambient temp below boiling point of gas.
H2O content in gas at the pressure change.
The CO2 thing sounds like it would work fine if regulated properly. The big question I have is how much faster will it cool than high volume ambient air, which seems to work quickly. I'm going to do some temp tests as soon as I can. I'm thinking CO2 is going to be more expensive than batteries, and the rig looks like more trouble to tote around. However, if the good outweighs the bad, I'm game. I can also see where something completely inert like Argon might be better than either one, but it ain't free either.
The convenience of the gas is almost half or little more is liquid so the conversion to a gas state gives you more for the volume.
You can actually cause abient air to be cooler just by reducing your supply at the very end causing a pressure increase.
Undeveloped country's use multiple cut off water bottles tops stacked in a window to cool down thier structures.
That's why the air blasting out of an air compressor tank is nice and cool on a hot day.
you guys that are stating that cooling the barrel too fast is going to ruin it are way off base. How fast do you think it heats up when you touch off a shot? We get anywhere from 500-5000 shots out a barrel before it is "ruined" by torching it with 3000 degree hot gasses (or whatever the exact temp is-some smokeless powders burn at 5000 F)
A friend of mine who is an ammunition manufacturer has used CO2 for many years to cool barrels down quickly. You blast them for a certain amount of time and then let them stabilize for 60 seconds or so.
I only use CO2 on nice walnut stocked rifles. My preferred method as AZshooter eluded too is to use ice water. I fill a 3 gallon Igloo cooler with ice from the ice machine and then fill it with DI water. As soon as I feel a barrel getting hot I walk over and hold it under the spigot, starting with the shank and working my way down to the muzzle. I then wipe it off with a towel and blow the water out from in between the stock and barrel. I wait 30 seconds and go back to firing.
Anyone who thinks taking a 416SS barrel from 140 degrees to 40 degrees in 20 seconds is going to have ANY detrimental effect on the metallurgy is very uninformed.
I know a couple of guys who use dry ice and alcohol to cool their barrels. They have deeper pockets than I do I guess!
I like to keep my range sessions as short as possible and in the summer here in Phx, you will wait forever and the barrel with still be hot! I've been doing this for years and it has had no bad effects and all good effects.
If You chill the barrel to minus 200 and then fire it I believe damage is likely. The cool temps I take my barrels too will never, ever have any ill effects.
I rarely ever only take one rifle to the range. I shoot one and cool it- letting it normalize while I shoot another rifle- often times mid-group on a real hot day and a light contour barrel. It sure speeds things up.
I just don't like to do it with wood stocks. If a rifle is full length bedded (Barrett Field craft for example) I make sure I let it sit at least 60 seconds so that the temperature can equalize all the way around the barrel. With a good floated barrel, the water runs all the way around it. I put the rifles away hot so that I know all the moisture has baked out at the end of the day.
Before you say we're uninformed have you measured the actual temperature of the barrel metal? If it is high enough, and I don't know if it is or isn't, rapidly cooling it could be making it brittle. I doubt that the temps are high enough that one time is going to matter much, but many times over the course of time could become a problem.
I have no horse in this race. I just want those who do this to do so fully informed about what they're doing.
Quenching, the process you are referring to happens when the steel is in the ~1,500F range, so it is definitely NOT happening in this case. The inside surface of the barrel quickly spreads the heat to the rest of the barrel. Gatling style machine guns can get that hot.
Yes, but what if it is 500°F at the bore surface when you start cooling? I can't believe that NOTHING happens to the crystalline structure of the metal when this is done even if you do start below the lower critical temperature. All of the H-T procedures that I've read say slow cool to room temperature or at least under 100°F. Those are specifically for tool steels, but it should be indicative for all steels.
Extrapolate that one-time event to doing it 50 or maybe even 100 times. Now what is the bore's surface metallurgy? All that I'm advocating is knowing where you're going before you get there.