Has anyone had any experience with this?

I just ordered a treated blank. My gunsmith won't say it makes them more accurate, he states he feels they will last a little longer, and string less when they are hot. This advantage/perception is small,...but so is the cost of treating the blank, so it's no loss if you try it and don't see a big difference.

If you search my previous posts you will find that it is mostly hype. Metallurgically it is nonsense.

mete - Interesting point of view. Actually Cryogenics is widely used in industry and the process is well researched and founded. There is no question that the cryo tempering process generates desirable benefits. Where the mystery lies is - does cryo tempering improve accuracy?

Here are the basics on cryo:

Cryogenic treatment has been around for several decades. It was developed specifically for industrial cutting and grinding tools. It was discovered that cryoed metals possessed greater wear resistence and it also increased the life of the tool (considerable operational savings were the result). In short order, the process was adapted to all types of metal objects from musical instruments, softball (metal) bats, racing engines, gun barrels, knives, and anything else metal you can think of.

Here is the science behind the process - Cryogenic treatment is designed to take ferrous and non-ferrous metals down to -300 degrees F at a controlled and incremental rate. Once this temperature is reached, it is maintained for 18 to 36 hours and then the part being treated is slowly returned to room temperature. Some treatments then take the part to +300 degrees for 3 to 5 hours and returned to room temperature.

The process is designed to complete the austenite to martensite transformation that occurs during heat treatment in steel alloys. Austenite is the soft carbon within metal and the martensite is the smaller and stronger carbon molecule which comprises steel. The concept is, if you can covert most or all of the carbon atoms from austenite to martensite, then the metal becomes more dimensionally stable, stronger, and more wear resistant. The process has been proven to work as advertised. There are tons of scientific articles on the treatment.

That is the science. Now, as with all basic scientific principles, they sometimes do not guarantee results in complicated models like a gun. There is no question that converting austenite to martensite is a good thing, but this does not necessarily translate to a more accurate wonder gun. Here are some observations on the process:

1. The time to cryo a barrel is before it is rifled and contoured. The barrel should then be retreated before the chamber is cut.

2. The end result is a more heat tolerant (stable) barrel. For varmint, bench rest, and high volume shooters, heat stability is a big deal. Cryoed barrels ��seem�� to hold zero better over a wider range of operating temperatures.

3. Many report that cryoed barrels are more ware resistant and seem to accurately shoot 50% to 100% more total rounds before the barrel is shot out. Throat erosion is a measurable benchmark for determining wear resistence.

4. Machinists who cut chambers report that a cryoed barrel cut substantially better than non-cryoed barrels. Many state that they can feel the difference while cutting.

5. My cryoed barrels clean noticeably easier than my non-treated barrels from the same manufacturer.

6. It would be difficult to prove that cryoed barrels are more accurate than non-treated barrels because of the many manufacturing variables from one barrel to another.

7. Cryogenics seems to tune barrel harmonics to a more uniform pattern. This is why musical instruments benefit so much from the process. Relieving stress within the barrel improves barrel harmonics which plays a considerable role in accuracy.

8. Way down on the list of possibilities is the very remote chance that by relieving inherent stress within the barrel, you can cause some very minor warping. If a stressed barrel was cut straight to begin with (most are not), by relieving the stress you can alter the bore. This has never been proven, however, the possibility exists in principle.

My opinion is that the process may refine some accuracy traits within your gun. However, it is not a magic treatment and will not turn a crappy barrel into a bench rest wonder gun. If you start with a premium barrel, there are some desirable benefits. Most premium barrel makers treat their barrels before they rifle and chamber so re-treating is not necessary.

At the end of the day, there are no factual reports of damaging your gun by treating the barrel. There doesn't seem to be any real downside.

Web sites:

http://www.300below.com
http://www.badgercryogenics.qpg.com/COLD_11699.html
http://www.diversifiedcryogenics.com

Zero Drift,

Very good data

I would only add that S/S barrels are made from 400 series stainless and 400 series stainless has a certain amount of carbon content. And 400 series S/S will rust (oxidize).

I use cryo in 99% of my applications, as a Tool & Die Maker. It definately "relaxes" the tool steel I use to manufacture tooling for industry. We have experienced increased tool life using the 300 below cryo process.

Whether cryo will produce a more accurate barrel, the jury is still out.

Don

Most of what I'm hearing and reading about cryo in barrels is either theoretical or anecdotal.

The only controlled test of cryo'd barrels I'm aware of was conducted by Kevin Thomas of Sierra Bullets and published in PS Magazine a few years back. He took barrels from the same run to make them as identical as possible. Had one cryo'd and the other not. He then used these barrels testing the Sierra Production runs using a machine rest. He blinded the test (did not know during testing which barrel was which). At the conclusion of the test, he found that the Cryo'd barrel was no more accurate than the non and did not have any longer accurate life.

A writer for American Rifleman also did a comparative test and concluded on the basis of a few groups and a difference in group size of a few hundreths of an inch concluded that Cryo did make a barrel more accurate. Knowing a few writers for NRA Periodicals, I think that a policy of supporting advertisers with positive comments was in action there.

Zero drift,the problem is that your 'science ' is not science at all."Austenite is the soft carbon " and "martensite is the smaller molecule" are totally incorrect. The process for steel is one of reducing the amount of retained austenite. However Groove Bullets' tool steel has retained austenite so it works on the tooling but the 4140 of a rifle barrel is very different steel and you would not expect any retained austenite. To learn more please read my previous posts.

I have no laboratory data and can rarely spell martensite, but for me its biggest advantage is in less-than-match grade barrels that "walk" when warming or cooling. Cryo stops that. Don't know why, don't really care.

In my many cryo'ed barrels, I've found it to be accuracy neutral. They seem to wear well too, but I can't attribute that solely to cryo.

I'll continue to use it where it's beneficial but it's use is not universal at my house. YMMV

Redial

mete - Argue with these guys - http://www.cryopro.com/what.htm

�Our proprietary deep cryogenic tempering process uses cryogenic temperatures (-300 degrees F) to transform the soft carbon (austenite) into a smaller and stronger carbon molecule (martensite). This makes the surface of the metal less porous, so there is more surface area to wear. When the process is complete, the metal is less brittle, stronger and much more durable than before. Tools can be Cryo'd when new or dull. Cryo'd tools are actually easier to resharpen because 50% less material is removed each time, so the tool can be resharpened twice as many times. If the tool is resharpened after being Cryo'd, it will cut much longer.�

Or these guys - http://www.cryoeng.com/images/WhatIs.HTM

This treatment, at -300�F for an extended period of time in a dry atmosphere changes the material's microstructure. Retained austenite (a soft form of iron) is transformed into hard martensite. A second result of the deep cryogenic "soak" is the formation of fine carbide particles, called binders, which are released and distributed evenly through the mass of material to compliment the larger carbide particles present before the cryogenic process. These smaller carbide particles help to support the martensite matrix. In addition, the deep cryogenic tempering process creates a denser molecular structure. The result is larger contact surface area that reduces friction, heat and wear.

Or these guys - http://www.ductile.org/magazine/2000_1/cryogenic.htm

What happens during Deep Cryogenic Tempering? (Ferrous components)

Most of the retained austenite is transformed into martensite. The martensite is then tempered to change it into tempered martensite. Small complex carbides called eta carbides are precipitated out. Residual stresses are greatly reduced.

Alloys with greater than 0.40% carbon REQUIRE Cryogenic Tempering to finish martensite transformation.

Or these guys - http://www.temper-master.com/Tempering.htm

Changes in tempered material will vary depending on the raw material used and the kind of tempering the item has already experienced. This process super cools material at a specified time/temperature (ramp) from ambient to -190o C. (-310o F.). Austenites, the softer molecules in the structure, are transformed to harder martensites. Maintaining deep cryogenic temperatures over an extended period of time allows for the formation of small carbide particles called binders (bainites) that are dispersed in the voids throughout the martensite, creating a denser, more durable material. These transformations work together to prevent wear caused by abrasion and friction.

Or these guys - http://nitrofreeze.com/faq.html#anchor2

What happens during deep cryogenic tempering?

During the process of deep cryogenic tempering austenite is transformed into martensite, which is then then tempered to change into tempered martensite. In addition, small complex carbides called eta carbides are precipitated out. This greatly reduces residual stress and promotes "micro-smoothing" of the surface.

I could keep going, but Saeed will run out of server space before I could post every cryogenic article on the Internet.

Zero Drift, I've already read all that stuff and I can tell you that most of it is BS.I speak as a metallurgist. What I've tried to do is to educate people and get you to be cautious about accepting advertizing hype.

Niels,
I have had two rifle barrels cryo'd.
The accuracy improved slightly mainly because the group did not string as the barrel heated nearly as much as before I had them cryo'd.
I shoot a lot of 300 to 500yard groups and this stringing effect is quite noticeable at that range.
With both these barrels the shots impacted lower and lower as the barrel heated. The cryo reduced this effect to about 2/3 of what it was before.
Just my experience.

Krieger does it to their barrels as do most barrel makers....that's good enough for me!

I am not a metallurgist - although I took several metalurgy classes as part of my apprenticeship - some 35 years ago. I think I know just enough about metallurgy to get myself in trouble, lol.

I do know that cryo (300 below) does in fact "relax" tool steel (relax is my non-technical term). Exactly how cryo does this, I am not sure. I remember back in technical school (in the stone age) when the teacher would tell us: If you want a stable grinding vise, mill it up, wrap it in grease and waxed paper and dig a hole, put it in the ground for a couple of years, dig out and and grind it. This will "stabilize" non-tool steel. What I "think" cryo does is basically the same process, but you don't have to wait years for it to happen. Cryo stabilizes the steel. Removes the "stress", if you will.

Somebody mentioned 4140. This steel is high carbon, non tool steel. Misserable stuff to work with from my standpoint. Being in the tooling industry I like and prefer tool steels. I wouldn't classify 4140 as a tool steel, although it may technically be classified as such.

I know that cryo works as I have seen the results with my own eyes. I had a part from a customer that was 18" long, by 8" wide, by 5" high. The tool steel was H-13, hardened to around 50 Rc. Anybody that has ever worked with H-13 tool steel is well aware of how much it "moves" during the heat treat process. The common, non technical term is - it goes like a banana. In any case my customer wanted a window machined out of the center of this hardened block that was 15" long, by 6" wide. After reviewing the blue print I called the customer and said: If I machine this window this block is going to: go like a banana (there is that non technical term). He informed me, the block was cryoed. I had heard of cryo before but never had any experience with it - at that point. I did as ordered and machined the block. When finished I inspected the outside frame of the block. I was amazed, I measured less then .0002" of bow in the sides of the block along the 18" length. Upon delivery of that block to the customer I was all questions. I have since requested cryo of tool steels from other customers. A lot of them have seen the results. Sorry for the long explanation here but it does prove the point that Cryo (300 below) does in fact "relax" the steel.

Most may or not be aware that as any steel is machined a condition called "work hardening" is applied. The more a peice of steel is machined, the more stress is placed into that peice. Cryo will releive those stress's. This is the reason I don't beleive in "fluting" a barrel. But thats another story. If a fluted barrel was cryoed, I do beleive it may help releive some of the stress created by machining the flutes.

Hope this info helps in understanding why cryo is used.

Don

Thanks guys. Your input has been very helpfull.
I have done some research myself.
Here in Denmark there is a small riflemanufacturer (Schultz & Larsen) You may have heard of them, they were a part in developing the 7x61 Sharpe & Hart and have made rifles for Scandinavia for years. Anyway they said that a "coldhammered" barrel(I am not sure if that is the correct term) can benefit from Cryotreatment, but that a cut barrel will not, since the stress in a cut barrel is close to nothing.
They also told me that around 20% of the Sauer cold hammered barrels that had been cryotreated in a test, done by the danish shooters association, was damaged by the treatment and that the remaining 80% had benefitted in accuracy.. They then went on and told me about a
treatment that will, "whatshamacallit", harden and polish a barrel inside and out, giving it longer life (tested a 6,5x55se had shot 8000 rounds and were stil going strong) the treatment also worked as a rust preventative as good as most stainless.
It sounded interesting
so I signed up for a cut barrel to replace my Sako standard stainless. I'll get it sometime this summer, I'll let you know what I think of it then. I am sure that I will not be firing 8000 rounds this summer though...
But I'll try..
Thanks again.

...I think it's called Chrome Plating

[ 03-30-2003, 11:21: Message edited by: Chris F ]

I wouldn't say it shoots better, but it will take about a third as much cleaning to keep it shooting good. I don't know a thing about metallurgy, but i suspect the talk about less change from heating up is probably true also since top drag racers are using cryo on entire blocks, cranks, etc. especially on motorcycle parts, claiming that it is more stable through the machining processes and doesn't change when hot.

After a good bit of anecdotal evidence, 25 or 30 barrels, I see no difference at all with a good barrel. It can have some effect on a medicre barrel that wasn;t properly heat treated to begin with. A metallurgist friend of mine investigated and said that if it had any effect at all on 416 grade stainless, it would probably be negative.

Zero - everyjting you put down seems to be advertising hype, not real world results.

Just so much bullshit to seperate a man from his money. God knows I've wasted all I'm going to waste on it.

Mete, I agree with you 110%. This is all marketing hype. It is senseless to argue with these guys though. You know the old saying, "A fool and his money".

Zero drift, just were does martensite reside in the crystal lattice of the steel? Just how is martensite formed? What is the chemical formula for martensite? Does steel undergo a phase change at low temperatures? If so, explain the phase change to us all.

You should be able to find all the answers on the web. Now once you understand these things go back to the BULLSHIT cryo websites.

Groove bullets, you are kidding right! You cannot possibly prefer working with tool steel over good ol' 4140! Tool steels are TOUGH, WORK HARDEN FAR TOO EASILY, WEAR TOOLS, ETC, ETC. 4140 cuts like butter compared to any tool steel! Even stainless is BETTER BY FAR TO WORK WITH than tool steel!!!!!

Axel

Axel,

Actually the steel I prefer to work with the most is D-2, hardened to 62Rc, cryo. I will explain further. One of my business's is a Wire E.D.M. Job Shop, E.D.M. stands for Electrical Discharge Machining. The best (nicest) steel to machine via the Wire E.D.M. process is D-2, S-7 isn't to bad either. I find that H-13 and H-21 cut a bit slower and 420 Stainless cuts even slower but does provide for a really nice surface finish. Any of the softer steels such as P-20, 4140, 4350, and the lower carbon steels such as Colled Rolled and Hot Rolled steels are the worst to machine via this process.

My other business is making Bullets, Groove Bullets to be exact.

I started out in E.D.M. back in 1968 and enjoy the work. I completed my Tool & Die Making apprenticeship in 1976 after working in several machine shops prior to entering a formal apprenticeship.

I have been programming, setting up and running Agie Wire E.D.M. machines for the past 18 years.

This will give you a better insight as to why I prefer working with hardened steel.

Don

Groove Bullets, that explains a lot. By the way do you temper the tool steel after EDM ? You do form untempered martensite in the EDM process.

Groove bullets, now that is a horse of a different color, so to speak. I understand your previous comments much better now. I was thinking, obviously enough, of more traditional machining operations.

Axel

mete,

Being a Wire E.D.M. job shop I machine parts for other company's. Therefor once I am finished with my machining of the part/component it is delivered back to the customer. They may or may not further treat the material.

Axel,

Oh yeah, grinding or hard turning or hard milling D-2 at 62 Rc would be a real pain in the butt, for sure. The grinders hate D-2, but I love it.

I also machine all sorts of exotic materials that are real killers on mills, lathes and grinders. Whats the cutting speed for titanium using carbide? Pretty low. But with Wire E.D.M. it doesn't matter. I also Wire E.D.M. a lot and I mean a lot of carbide. It cuts slower then D-2 but the finishes, wow, if a fly landed on it he would fall on his butt, lol.

Have a good one,

Don

i had 300 Below do a .22 Hart barrel for me once and it was just the sweetest thing to run a patch down that barrel. Smooth as a babies butt.

It seems to me that it would be much cheaper for the manufacturer of barrels to do it, than the consumer.

If it is beneficial and the barrel is worth the effort, the barrel manufacturer should do it.

I can't imagine a situation that the consumer should have it done.

PacNor does it on-sight for $40. If that's the last $40 I ever waste, I'm ahead of the game.

If it cleans easier, but lasts no longer or shoots no better,....that's still worth $40 to me.