deep cryogenic treating of barrel and bushings
I have been asked to help a friend that works for a company that is set up to do cryogenic treating. I have been trying to think of some un common uses.
Do you think cryogenic treating an AF barrel and attached bushings would make it more accurate?
Can you think of any advantages or disadvantages of me trying this?
I know an air rifle doesn’t heat up like a powder burner, but it is still stressed right? Who knows it may increase my velocity by a few fps?
I wonder if I can send ½ a tin of 500 .22 JSB Exacts pellets through the system, and see if they shoot better than the other half of tin?
Any other parts I should consider letting helping them test?
If I help him, I will get to run some stuff through for free 😀
Thanks,
Roger
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Lija cost $45
Q. What is your opinion of the deep cryogenic processing of barrels?
A. The cryogenic treating of barrels at a temperature of -300 degrees below zero has been a hot topic of discussion lately. Our short answer is that it will not harm your barrel but we are not completely convinced of all of the benefits claimed by some. The only benefits that we feel are likely to result from the treatment are possibly a longer barrel life and a slight increase in machinability.
Claims for increased accuracy through stress relief are not founded in our opinion. When barrels are button rifled no material is removed, it is just displaced. This causes stresses to be formed in the steel. If these stresses are not removed problems will result. These negative conditions include warping of the barrel during other machining operations, an increase in the bore diameter towards the muzzle end of the barrel during the contouring phase, and in the extreme, lengthwise splitting of the barrel. Also, if there are stresses remaining in the barrel they can be slowly released as a barrel warms up during firing. This causes the barrel to actually move during the course of shooting, causing inaccuracy.
In our testing we have found that the only effective means to completely remove the types of stresses introduced during rifling are with conventional heat treating using elevated temperatures. The -300 degree treatment alone will not remove these stresses. We have been told by a knowledgeable metallurgist that the deep cold treatment will, at best, remove up to 6% of the remaining stresses in the type of steel used for rifle barrels. The key words here are remaining stresses. In other words if the barrel was not stress relieved conventionally, then only 6% of the original stress will be removed. If the barrel has been treated conventionally with heat and then brought through the -300 degree cycle, up to 6% of any remaining stresses could be removed by the cold treatment. We do know through our testing that the cold treatment alone will not remove any significant amount of stress and that the problems outlined above concerning stress will remain in the barrel.
So, because of the very limited amount of stress that could be removed with the cold treatment (if the barrel has been properly stress relieved with heat as our barrels are) we do not believe that there can be much if any accuracy benefit to the -300 degree treatment of our barrels. It is for these reasons that we feel the cold process has very little potential for increasing the accuracy of our barrels. In our opinion, other than the removal of these stresses, there are no other mechanical factors involved that could benefit accuracy in a rifle barrel, resulting from a heat treating operation, either hot or cold.
For reasons not completely understood however there may be an increase in the wear resistance of the steel. This type of wear however does not contribute greatly to barrel erosion. We invite you to read our comments on this type of barrel wear in the question regarding the use of moly coated bullets.
Another possible side benefit to the freezing process is a slight increase in its machinability.
Post Script: Since I originally wrote this an excellent article by Kevin Thomas of Sierra Bullets was printed in the September, 1998 issue of Precision Shooting magazine. Mr. Thomas found, in a controlled test, that there was little benefit to deep freezing match grade barrels. He could see no difference in accuracy but probably a slight increase in useful life. I would encourage anyone interested in this subject to take a look at this article.
I didn’t finish reading all the comments here on this thread. I use Cyro in my business as a full time Knife Maker. Your Buck has already been given the cyro treatment. Mr. Paul Bos is the heat treater for Buck. Your YO knife is more than likely treated as well.
We use it to increase the Rc hardness by one to two points and to further to reduce stress. However, the draw cycle relieves most of the stress in the first place. Which your bbl. if Hi-carbon steel has already received. The stainless bbl’s go thru a normalizing cycle after rifling. So It is doubtful you will gain very much at all.
I’ll almost bet that your bbl, if stainless, has been as well. If nothing else, it has been normalized. You could very well induce warp in your bbl. by cyro, especially if not introduced into the liquid nitrogen correctly.
M. Lovett
Maker
The
Loveless Connection Knives
Since I would currently have to pay for such services, I have never done it to anything.
I live in England where everything is frozen for free on a daily basis.
My brain is 10% harder,20% more dense and has been known to work for over 3 weeks before faliure.
If cryogenics cures all warped and twisted things, then Okayas needs a cryogenic suppository…
It’ll solve that problem reeeeeaaal quick..
I think I need a cryogenic brain treatment, perhaps it will relieve some stress in my life. Maybe it will keep me sharp in my old age, as it keeps a knife sharp??
My wife has always said that my brain is “warped”.
Mark
Dunno really, but I hear it works wonders on springs.
It’s basically a reverse heat treatment… You super cool it slowly and hold it at a set temp and then bring it back up slowly several times… Nice thing is you can do things that are not metal and you won’t melt them…
People have cryo’d panty hose to extend the life by a factor of 50…
Brake rotors are cryo’d to make them wear less and be less prone to warping…
Before cryoing a barrel I would lap it to be sure you don’t have any burrs or raised edges, once you super freeze it, it gets harder…
If it were free, I would cryo treat lots of stuff with questionable benefits, such as an airgun barrel. Of course my powderburner barrels, car parts, and everything else too.
Since I would currently have to pay for such services, I have never done it to anything.
I dont think the lead pellets will benefit..your barrel sure..I used to re grind shear blades for a flying shear that sheared steel tubes that came off of a tube forming mill..say that real fast.. I would grind about 15 per week..one day a deep freezer guy stopped by and started freezing the blades. My grinding went from 15 per week to about 5 per week..they would last forever..One guy who does it said he froze a bic razor and shaved with it for 3 weeks before it got dull, I know some guys who freeze their go cart motors..I have had some endmills done but couldnt tell much difference just because we are always doing different jobs and not many long run productions jobs where you could do good test..
Maybe the process works similar to homogenization, or when you heat metal to near melting and hold it there for several hours. The alloys distribute themselves evenly throughout, making for a “homogenous” peice of metal.
Dunno really, but I hear it works wonders on springs.
Cryogenic treatment is used in a barrel to relieve stresses caused by the rifling process. Much the same as heat soaking the barrel in an oven and then allowing it to air cool. The idea is to keep the barrel from bending and changing the point of impact as it would when cartridges are fired in an un-stress relieved barrel. It’s really meant for rapid firing “powder burners”. But hey, if it’s free, I seriously doubt it will hurt your barrel. Give it a try… Let us know if the relative accuracy of the barrel changes.
Happy shooting!
I only know cryogenic treatment from it’s application on brass music instruments (I play the trumpet).
In this field, it is used to ‘cure’ the instrument after it has had a repair, or if it’s a rather old instrument. It is meant to ‘resettle’ the molecular structures of the material after it has been stressed, bent or dented.
When a metal gets bent, stressed or dented, the molecular structure ‘snaps’ between layers, and the layers move half an atom or so apart, towards the direction of the force applied. This affects the harmonics of the structure of the metal, negatively (albeit minimally) affecting the sound quality of the instrument.
And cryogenic treatment is said to ‘heal’ the molecular structure of the metal once more.
Since there are some rather violent production processes involved, this could have a positive effect (again a minimal effect though) on the barrel.
Or it could completely disrupt the purpose of those production processes, I’d say it’s about fifty-fifty 😆
Thanks for the update, I’m not a brain when it comes to tech stuff, only your poor white trash.
Maw its proven that cryogenics increases blade life on knives and razors. I also know that the olympic shooting team is testing cryogenics on their equipment. From my very limited knowledge cryogenics basically makes metals become tighter together on the molecular level making it less likely to have deviations in consistentcy. just my 2 cents.
Well then, maybe you should try some foods.
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Yep, the very slight gain in Rc. Hardness would possible lead to increased bbl. life. But we would never be able to measure it in an air gun. It UN-likely you could gain much life in th hottest of powder burners. What you can do is crack the surface of the rifling. Not likely either. But very possible!
Mike