I'm still building my first custom rifle in my mind as I wait for my Montana action to arive.
In the latest issue of Rifle Shooter they have an article on accurate barrels. In it they said "Cryo treatment never makes a barrel shoot worse, and often it dramatically improves accuracy"
What's the word out there on this deep freeze treatment?
I'm not looking to build a bench rest rifle but is it worth spending a few extra bucks on a good barrel and then having it Cryo treated to enhance a hunting rifle?

You might check my previous postings on the subject. Speaking as a metallurgist it's nonsense. But you might consider the comments of two long term and highly qualified barrel makers; Shilen and McMillan, they would love to find something that would make their barrels more accurate but they have tried cryo and found it doesn't work.

I think Shilen and McMilan and Kreiger are responding to the feeding frenzy over cryo. They might as well get the money for the work rather than sub it out. I have only had 3 done and it did nothing. I do not have that much experience with it to form an opinion.

If a barrel is properly made in the first place, the residual stresses in the metal will be fairly minimal. But if it is screwed up, there may be significant residual stresses which cryo treatment will relieve. Cryo treating a good barrel is like using acne medication when you don't have acne.

We all know that one barrel isn't proof by any means, but......
I have a Sako AV that strung shots from center to 10:00 in a wonderful little arc. The first and third shots were always about an inch and a half apart. The warmer the bbl became the further the shots strung out. After five the string was about three inches. It is hard to get a bbl to cool when it is 100* outside. I sent it in to get stress relieved. Using the same load, three weeks later, after stress relief the groups shrank to an inch for five shots. There was a group, not a string. A cold bbl will shoot to the exact spot it shot to a week or a year ago. It never did that before. Even if I just got lucky, the confidence I now have in that bbl and load made it money well spent. Good luck......

I've never seen it help a good barrel.

Well, I'm NOT a metalurgist, but my understanding from reading extensively on the subject, is that cryo treatment will remove about 6% of the retained stress after the heat relieving process is complete. The beneficial changes that occur as a result of the heat treat process do not actually take place during the heating, but, rather from the cooling or "quenching" from the high temperature. The cryo process dimensionally stabilizes metal by eliminating most of the austenite. Molecules realign themselves to form a more coherent status with each other. The redistribution closes and refines grain structure in metal allowing for increased resistance in wear. Whether or not this actually enhances accuracy in rifle barrels is subject to ongoing debate. I don't know of anyone that believes that proper cryo treatment can harm a barrel, but many are convinced that it can improve accuracy in some barrels. The #7 Shilen Stainless Steel Select Match Grade barrel on my 20BR has received cryo treatment. This is something my gunsmith did on his own before threading, chambering, or crowning. This rifle shoots itty bitty groups, but I don't know what it would have shot like without cryo treatment. It may or may not affect accuracy in your new custom rifle, but cryo treatment makes for easier machining and a more durable metal surface.

SST, here I go again . Metals do not have molecules nor do they have molecular bonding. Retained austenite in 4140 ?? show me the study that has measured , with xray crystallography, retained austenite in 4140.

I had the cryo treatment done to 2 rifles, a 300 Winchester, and a 7mm Magnum. No appreciable difference in accuracy was observed. Both rifles shot well before the treatment-1" groups at 100 yards. They still shoot the same.

mete,
I was merely relating what I've read on the subject. Like I said, I'm not a metalurgist. I will, however, disagree with your statement that "Metals do not have molecules...". I have my shortcomings, but I've studied a fair share of science over the last 50 years. All matter has an atomic structure that includes molecules. A molecule is simply the smallest particle of an element or compound that can exist in a free state and still retain the characteristics of the element or compound. The molecule of an element consists of either a single atom, or two or more similar atoms. Molecules of a compound consist of two or more different atoms.

I have Rem Model 7 in .205 Sav. that I put together with a barrel from a Rem Classic. I had the barrel turned down to a very light contour. The gun would string shots all over, 4" groups at I00yds. I gave it to a friend who's into reloading and making things shoot. As a last resort he had it cryoed. Now it'll put 5 shots together in an inch. Thanks Mike!
Someday I may get it back to shoot again.

[ 03-09-2003, 10:26: Message edited by: Recoil Rob ]

SST, I suggest you research the basic types of bonding ( chemistry 101) there is a major difference between covalent (molecular ) and metallic bonding.

mete,
Interesting discussion. I had no intention of getting into specific deliberation of cations or anions. I understand that sub-molecular relationship. If you reread my original post, you'll see that I made no reference to metallic bonding.