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Aragorn
20 February 2011, 18:11
Cryogenically treated barrels. My understanding is that cryogen treated steels benefit from increased strength and hardness. I also read that in barrels it gives you greater cold bore shot predictability, minimizes thermal drift, and extends barrel life. According to wikipedia, and everything else I find, cryogenic hardening is simply taking the austenite in the steels crystal structure down through a transitional state and turning it into martensite. It's this increase in martensite which yields the increase in strength and hardness. The austenite appears to form during the heat treatment when the steel is taken above the transitional state temperature, and it is the quenching that turns it into martensite. Quenching is usually done to room or ambient temperature. At room temperature most medium carbon steels and low alloy steels undergo 100% transformation, however high carbon steels and high alloy steels still retain austenite at room temperature. Cryogenic hardening is simply quenching to achieve a 100% transformation in high carbon/high alloy steels.

Reading that it makes sense that it could extend barrel life. The question(s) is/are though, how well does it work in rifle barrels? How hot does the heat treatment get when a barrel is being made? How would it affect cold bore shot predictability and minimize thermal drift? What effect would it have on a cold hammer forged barrel?

I asked my crystal ball these questions, but when I did it exploded.

Uglyduck
20 February 2011, 18:55
I'm of no help other than to suggest you contact JP rifles as they use cryo barrels. They might be able to help.

henpecked
21 February 2011, 09:18
Heres my take on it....just my .02 cents

I use this
http://www.meta-lax.com/
You can even leave the scope on the gun during the process.
I can tell you that the bullets do not walk as the barrel heats up. (heat amplifys stress)
The fellow that has this uses it on sprint car frames and engines, plastic injection molds and gun parts.

cryogenics does not take the stress out of the barrel. cryogenics does change the metalurgy of the metal making it tougher not harder.
Rockwell testing of the metal will not change after cryogenic treatment.

If you need more information shoot me a PM and Ill put you in touch with this guy.

Steve

sniperfrog
21 February 2011, 18:20
About 8 or 9 years ago, there was an article in Precision Shooting magazine about this. A guy that does all the QC for Sierra bullets put cryoed barrels to the test. He had 3 Hart SS barrels all cut from the same bar stock and rifled with the same button and chambered with the same reamer (308Win) etc, etc. He had 1 cryoed and he also had a Blackstar barrel which was cryoed (they entered a barrel for the test), the other two were left alone. He had another guy mark the barrels so he wouldn't know which was which. Anyway, long story short, the cryoed barrels didn't last any longer than the non cryoed. They started throwing rounds at about the same amount of rounds (around 4000) as most of the 308 Win test barrels he's used over the years. In fact, one of the non cryoed went the furthest. This guy shoots all day long testing bullets. He said that some barrels will shoot out early for no apparent reason and some will go on shooting forever. Cryo makes no difference.
Now I have heard that cryo treatment helps the drill stay centered better when drilling the bore and some gunsmiths say they chamber a little easier. But that's about the only benefit.

Aragorn
21 February 2011, 20:24
Thanks for the info guys. I think you pretty well answered my questions.

CGS
12 August 2011, 06:01
Hi guys this is my first post. I was doing some research on cryo barrels and this thread popped up. I just wanted to add in my 2¢ to the subject, as if it mattered. :)

I think the thought process in this thread is that cryo barrels will last longer, but I do not necessarily think that is the purpose of cryogenically treating the barrel. I am no expert on the subject, but when I was an apprentice tool and die maker in my early 20's, the old timers would throw parts out in the snow for a few days or put them in the freezer for a few days before making their final grinds. They'd primarily do this with their jigs and fixtures where precision was important. When I asked why they explained it that, making the parts cold realigns all the atoms in the metal and makes the metal more stable. This thought process also seems to be why people cryo treat their barrels.

Again I am no expert but it seems (from what I have read) that a cryo barrel will maintain zero longer as it warms up than a barrel which hasn't been cryo treated. I found a couple good links on the subject but I am not going to post because this is my first post and it's not my intention to spam. I could also be way off base but it seems like several manufacturers cryo treat their barrels, including Benelli and claim to get better accuracy.

Based on the assumption that a cryo barrel will have improved accuracy, not improved longevity, I am curious as to everyones thoughts.



Here's another thought. If someone takes a cryo barrel and puts it to a machining process, for example removing diamater from the barrel on a lathe or threading the muzzle, would this cause enough heat to ruin the cryo treatment? That's actually what I was researching when I stumbled across this thread. How much actual heat would be necessary to ruin the cryo treatment?