barrel treatment

[Kellysk8s 6]

Has anyone had thier barrel treated by 300 below and do you recommend thier services?

[308SAIGA 55]

Never heard of it until now, interesting.....

[DrThunder88 912]

I'm not sold on liquid nitrogen treatments for gun barrels. Anecdotal evidence of accuracy increases ranges from negligible to significant. Unfortunately these informal tests are severely flawed as experiments and the results must be viewed with healthy skepticism. I'm also skeptical of claims of increased wear resistance. I don't know much about metallurgy, but I am familiar with the use of cryogenic treatment to convert leftover autsenite into martensite in high-alloy steels, which non-stainless gun barrels usually aren't.

 

I'm also not sure how the chrome lining of the bore wold react to the treatment. My gut tells me it would be unaffected, but checking with your barrel treater is advisable.

[kresk 10,063]

Have read about cryo-treatment but don't see a lot of folks going for it.

[macbeau 902]

It used to be called "cryogenic stress relief" and I had it done to a factory Rem 700 barrel as part of a broader rifle package service from Briley in 1996. It's supposed to work kinda like reverse heat treating and it supposed to align the molecular structure of the steel to reduce tight spots, add hardness and give more even heat distribution. It seems (seemed) to work best on bolt guns. My rifle was shooting ~1" and came back as a solid 1/2" gun (that I still have).

Cryo-treating seems to have waned in popularity, but it was pretty expensive (around $200 in 1996) and most folks just pull and replace the barrel with a Douglas Air Guage or a Hart or something similar if it's a problem.

I think it works, but there are probably any number of other more cost effective means to achieve the same result. The Browning B.O.S.S. comes to mind (which tuned (or tunes) the barrels' harmonics /vibrations to the load used)...

 

Macbeau sends...

[pbwe 45]

The only metallurgical effect that I would anticipate with cryo treatment would be to transform any residual austenite in the steel matrix to martensite. This assumes the barrel processing control permitted the austenite to persist from elevated temperature processing, which indicates poor production values or control. Introducing untempered martensite in the matrix introduces localized residual stress fields, rather than remove them.

 

As regards hard vs soft materials, it should be remembered that while the strength changes, the elastic modulus (the deflection associated with a given force) remains the same. Hardening a steel permits it to tolerate larger forces without deformation, but within the given metal's elastic range, both hard and soft variants of a given sample will exhibit the same amount of deflection (e.g. resonant displacements will be the same).

 

Stress relief occurs through the dissolution of dislocation structures within the crystal matrix. This is a [elevated] temperature activated reaction. As far as I know, there is no peer reviewed research to show that dislocation structures are removed by cryo treatment.

 

As far as dimensional stability goes, the differential cooling (not all points in the volume cool at the same rate) and associated thermal shock may itself introduce bulk plastic deformation during the moment of quenching in nitrogen. And the occurrence of plastic deformation means that the initial shape is not the final shape.

[csspecs 1,987]

I think I'd opt to spend that $300 shooting the rifle. Its a saiga, there is a limit to what your going to get out of it.

 

 

If I was in a quest to tighten my groupings, I'd probably start changing the front sight block. If you really wanted to see improvements, then you also have to come up with something to remove the stress from the gas system.

[Kellysk8s 6]

The price I was quoted was $ 109.00 and $ 20.00 for shipping for 2 guns including bolts and carriers. Still looking for more info, have read a few artiles from differnt gun mags that were posted on the websight. Thanks for the replies.

[paprotective 362]

If they are close to Michigan maybe they just toss them in one of the 'great lakes' on a string.. wait a few hours and fish them out..

[csspecs 1,987]

$109 wow, thats kinda cheap. Do they press the barrels out of the trunnions to do it? Just seems like a lot of work for the money.

[Kellysk8s 6]

$109 wow, thats kinda cheap. Do they press the barrels out of the trunnions to do it? Just seems like a lot of work for the money.

 

Actually they are having a special right now, that was the price for my .308 and shotgun, and they treat the barrel/ reciever and the bolt and carrier. This was in the email I recieved. The trigger group has to be removed and all plastic.

[PTGT_Neon 1]

It's a good idea to remove all springs too.