TTAG to Test Cryogenic Rifle Barrels on Underground Tactical Build

1. Pretty cool – but this isn’t a particularly unique process anymore. I believe that Patriot Arms cryo treats all of their barrels, and even some of the mainstream companies like Rock River Arms does it on their competition rifles. It’ll be interesting to see the before/after results at any rate.

   • Benelli also claims it’s what makes their shotgun barrels so amazing.

2. I’m unconvinced, but the Mini guys over at Perfect Union swear by this. I’m curious to see the results, but I’d rather see a larger sample size though, maybe 4 untreated vs 2 treated in some kind of double blind.

   • Definitely need a control in there, guys.

3. Cryogenic stress relief basically gives you the same net effect as more traditional heat treatment methods. I’m not sure how residual stress in a barrel would affect accuracy in either direction, but I look forward to the testing to find out.

4. I’m hooked on the process. I’ve only tried it on 2 bolt guns tho.
   It changes barrel harmonics in a good way. Neat stuff. I think you’ll be impressed.

5. It is April 1 today.

   • We’ve already had our fun. Down to business.

     • I’m waiting for the follow up “April Fools, got you again”.

6. “Tempering” is a bit of a misnomer here. It’s really just quenching to lower temperatures to get a more complete martensitic transformation. Better hardness equals better wear but what’s effect on toughness?

   • Really depends on how their process is set up. Most of the marketing hype on cryogenic stress relief equate it to a quench process, but there are a lot more heat treat processes besides “heat it up and drop it in oil.” It really sounds like what they’re going for is closer to annealing than quenching.

     • The heat treatment process for steel:
       1) Austenize – take the steel up to the point at which it transforms from the BCC to FCC crystal structure. The steel will no longer be magnetic at this point. The FCC phase can hold a lot more carbon in solid solution than the BCC phase and so the carbides dissolve into the iron. There is some grain size refinement at this point too, but that gets more complicated.

       2) Quench – rapidly cool to below the martensitic transformation temp. The FCC crystal structure will not have enough time to let the carbon precipitate out of the solid solution as carbides, and so will get stuck as a supersaturated BCC structure. The high concentration of carbon in solid solution puts a lot of strain on the lattice, making the material very hard but very brittle. Not all the austenite will transform to martensite. The amount of retained austenite is dependent on alloy and quench rate.

       This is where cryo treating comes in. By super cooling the steel, more of the retained austenite will transform to martensite.

       3) Tempering – heating the steel back up a little bit will allow the carbon in the martensite to precipitate out as very evenly dispersed, very fine carbides, for maximum strength and hardness. Too much heat and you will form large carbides which reduce the strength but increase ductility and toughness.

       If you do not temper after a cryo quench, you will be stuck with martensite, This will be brittle and prone to cracking. A tempering operation is critical following a cryo quench.

       There are two reasons cryo quenching is supposed to be better. 1) By getting a more complete austenite to martensite transformation, you will get more tempered martensite, so overall the steel will be harder/stronger. 2) The BCC and FCC phases have different coefficients of thermal expansion. When the retained austenite heats up, it expands differently than the tempered martensite, which can cause warping or distortion. By having only one phase, the thermal expansion of the barrel is homogenous and so warping will be reduced.

       • All of which can be summed up as

         but there are a lot more heat treat processes besides “heat it up and drop it in oil.”

   • While that’s a common misconception, it simply isn’t correct. Check out the 300Below website -they’ll run you down the science (at least that which is understood).

7. Across the country there are tens of thousands of livestock farmers using liquid nitrogen tanks to store frozen semen for artificial insemination.

   I don’t know if this process is any more complicated than dipping a barrel in a nitrogen tank, but I gotta wonder how many gun owners will try this at home.

   • I’ve got my 1911 in the freezer right now. I also put in a box of ammo and my holster. I figure go hard or go home, right? Of course the wife’ll freak out a little bit when she sees a bunch of frozen food on the counter when she gets home but whatevs.

     Will it help if I play Disney’s “Frozen” on repeat? I’ll test the results of playing the movie vs. the soundtrack and report back…

   • I thought I saw a video somewhere of a guy firing a Glock while it was frozen in liquid nitrogen.

     Which is good to know.

     • Once, I put my Glock 19 in dry ice. It seized and it was impossible to manually cycle it until it thawed a bit. Since then I put around thousand of rounds through it without problem.

       • Dry ice forms at about -109F. That temperature is not even close to cryogenic temperature. About 200 degrees colder is required.

   • This was the earliest form of the practice, which almost never works. The temp drop and raise need to be controlled and managed – also you want to avoid direct liquid contact. For more info, check out the 300below website.

     While I’m happy to see this (finally) hitting the wider audience, cryogenics as a hard-core top end aerospace process has been in place for 50+ years. I’ve been treating firearms, and racing parts for the last 2 decades.

8. I did a test just like this a bunch of years ago. What we found was that the cryo tempering worked really well for lower quality and factory barrels and had hardly any effect on high quality match barrels.

   The cryo tempering relieves internal stresses in the steel. Thus there is less movement and warping of the barrel as it heats up during firing.

   If you have an expensive custom rifle, cryo treatment is not worthwhile and will not greatly improve accuracy. If you have a basic or inexpensive rifle you want to shoot better then cryo treatment will probably have a good effect on the barrel.

   • So it effectively does (to a certain extent) the same thing as a heavy or bull barrel, in that the barrel flexes less, leading to increased accuracy?

     • This pretty much what the Mini shooters say. Alot of ’em use this in conjunction with a strut to reduce flex / whip in the older pencil barrel Mini 14s. Supposedly you can get them down to 3 MOA that way pretty consistently.

   • Did you do your finish machine and rifling before, or after treating? Who did the cryo? Did they use different temps and times by barrel material? Was it one of the wet-spray machines? How did they position the barrels in the chamber? Were they spaced properly? What was your testing procedure?

     I ask these questions because I know the answers when I hear someone say, “I did cryo, and it didn’t do anything”.

     Cryo is perhaps one of the most effective processes that even after 50+ years of successful use, we still have trouble fully understanding and explaining. There’s no arguing it doesn’t work, if it’s done properly. From fighter jets to satellites – the military has been on it for decades. So has Formula 1, and pretty much any race series builder who wants the parts to be the strongest and highest wearing they be. There’s mountains of research proving it’s functionality – but like lots of things, the average Joe engineer doesn’t understand it, it goes on the backburner for the mainstream.

9. Oh crap! This actually reminds me that 300 Below’s Tactical Triad cleaning kit is now officially on sale AND they have offered a discount to TTAG readers. I’ll make a separate post for this soon.

   But… review here: http://www.thetruthaboutguns.com/2014/02/jeremy-s/ttag-exclusive-tactical-triad-cleaning-kit-300/

   Available on Amazon here: http://amzn.to/1iFE0mY

   10% off coupon: TTAGTTAG (valid through April 30th)

10. What does this have to do with my 1953 Combat Masterpiece?

11. Shilen Rifles claims the process does nothing to enhance accuracy, based on their testing.

    http://www.shilen.com FAQ #1

    Should I “cryo” my barrel?
    If you have heard that the cryogenic treatment stress relieves steel, this is false. We have measured the residual stress in 4140 and 416 steel with a process called x-ray diffraction. After much R&D, we have not been able to measure any changes in molecular stress after cryo treatment. For this reason we do not endorse the cryogenic process, but we can safely say that it is not detrimental to the barrel either. “

    • Really, that statement doesn’t say anything about whether cryo treating can affect accuracy. It just says in those two specific types of steel they weren’t able to find a difference in stress. Stress is one thing but not the only thing that is supposed to change from cryo treat. And/or maybe it has a different effect on other grades of steel or on steel that is hammer forged vs. other methods of production. Maybe they tested an ingot of steel and it didn’t matter, but if you turn that ingot into a barrel and push or cut rifling grooves into it, do other machining, etc, THEN you end up adding stresses to it that cryo treating relieves.

      Too many variables, honestly. Shilen’s comment there is too narrow in scope. The real question is whether or not it changes accuracy in real life, anyway. I don’t care what an x-ray or scanning electron microscope shows and I don’t even care if I understand why cryo treating changes anything, if it does. If it works it works. Period.

      …and I have personal experience with it working on brake rotors and other car parts so I’m not particularly skeptical that it will work on gun barrels or some gun barrels. Accuracy is one claim that I would want to see proved and I look forward to this TTAG test big time, but I fully believe that barrel life would be enhanced based on what I have seen in high performance brake rotors.

      • Jeremy S, It’s good to see someone understands. Shilen tested for one tiny dimension, I have no idea if they even did that correctly. IF done correctly, a cryo treated barrel will last longer, clean easier, stay more accurate as the barrel heats, and be stronger. If done improperly, it will not produce those effects.

        There’s no arguing against what properly executed cryo can do. It’s that people (and those who do it) don’t understand fully how it works that has kept it reserved for the cognoscenti ,high-end aerospace, and racing. It doesn’t matter exactly how, just that it does.

        You’re right, it works on rotors. It also works on blocks, rings, cranks, valves, heads, bearings and a host of other racing parts that are tasked with being as strong and long-lasting as possible.

    • Might be related to what PeterC2 says above.

12. Old news. That’s how Sinter Fire manufactures their “frangible” bullets.

    They dip them in a vat of liquid nitrogen so that when they strike a solid object they break apart like similarly treated rose bud shatters when hit by a hammer (as seen on the Discovery Channel). 😉

    • I’m pretty sure materials subjected to extreme cold in nitrogen only remain “frangible” as long as that low temperature is maintained. Dipping a bullet in nitrogen and then allowing it to warm up to room temperature again should have no effect whatever on its frangibility.

      Or, enough with the April Fools crap, already.

13. Just a thought but for a durability test perhaps Dillon could bet persuaded to put a few barrels into an Aero or two?

14. Why are they partnering with a company that doesn’t manufacture the barrel? After all, it is the barrel that counts in this cryo treat process. Don’t we need to know who’s barrel is being used? Just guessing, this process would seem be more effective in a hammer forged barrel than a button rifled barrel. Pounding on steel imparts a lot of stresses–which is why tempering was used with steel swords a couple of millennia ago–failing to relieve the stress results in early failure (breakage) of the blade. After that, the changes in steel caused by the tempering process are beyond my meager understanding, other than that the steel is harder afterwards.

15. Wanna know what’s REALLY stressful? Being in a civil emergency without guns.

    If I should find myself in some sort of New Orleans situation and they come for my guns, that’s the day I and several of them die. Because I’m shooting until one of them takes me out.

16. I don’t know if it will make guns more accurate but cryogenics will change the metal properties. When steels are heat treated and you let them cool to ambient temperatures, that cool down process does not stop because as far as the molecular structure is concerned, room temperature is still about 530 degrees above absolute zero. Cryogenics speeds the cool down process up, otherwise the heat treatment process would take a thousand years (give or take) to fully effect the metal’s grain structure.
    I’m not saying it’s worth it, just that it does indeed changed the metal.

17. I can’t find the followup test results to this. Was it ever published?

    • Yes ,, where are the test results..

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