Well, -300F IS.................
TRUE Cryo, but even lower, -305F to -315F can be even better in some cases, I'm told. Additionally, the super-cold regions are defined as -244F and below.
Now, referring me to an article about Cold and Cryo treating that was written in 1991, and last revised in 2001, and in handbook #4 isn't doing anyone any good at all. I'm not too 'puter savvy, or I'd have sent the PDF, if I'd had the time; but I'd suggest you read that LATEST article, which was revised NOVEMBER, 2013 and published in Handbook #5 (NUMBER FIVE) this will provide the latest information available, and its only four pages, and is all PEER reviewed.
What I'll do in the future is to have the barrelmaker I choose, to send a raw slug of steel to have it cryo'd and then begin machining it into a finished barrel, and maybe this will stop the springing open of the bore as its profiled, who knows?
Kathy Bond is a nice person, and I'm sure Hobie is, too; however, they do not have, and she said there's no plans to, acquire a V-I machine (too expensive), and her customers tell her they get "...all the benefits...", but, therefore remains the INability to run a proper Cryo treatment from the standpoint of economics and the ability to maintain the time and temperature necessary to complete the task required. Using CTPs process, barrels are typically held at temp for 20 hrs.
IF you read the latest definition of "Cold and Cryogenic Treatment of Steel", it provides you with the latest comparison between COLD treatment, and CRYOgenic treatment of steels. this is the definition (it DEFINES the process) of cryogenic processing that ASM accepts and presents as the necessary way to perform the process so that all the requirements and benefits of Cryo processing will be realized, from the get-go, and with NO excuses.
As far as spraying LN into the area where your product is, well, this is THE reason most people say, ".....an' that (**&^&^%$%#@##$% don' work", or, "I cain't see any great diff'urnce A-tall..." The next reason is because a non V-I machine isn't economical, the cold will collect in the corners of angular machines and wick out there fastest This is WHY some have downed Cryo, because they haven't received what they'd paid for. (This info is on the first page of the new definition.) You must also realize, if you ask a "processor" what kind of machine he has, and/or how long the process runs, and how long is the part(s) held at temperature, and they say something like, "That's proprietary, that's an in-house patented, confidential knowledge an' you don' got th' clearance" well, RUN, don't walk, AWAY. Call Rick sometime and ask if he has the time to give you some background, or, better yet, go here:
http://metal-wear.com/
As far as shotgun barrels are concerned, they should be joined w/something better than soft solder, but w/trap guns, one of the benefits realized would be the stabilization of materials so that the predominantly-fired barrel will not be straining (and flexing) against its partner, which isn't suffering from a similar but not as drastic a condition.
As far as a Cryoed barrel not lasting, well, besides barrelmakers having no incentive to make a longer-lived, or harder barrel of more heat-resistant steel, (like MG barrel steel), because they want to be able to "turn 'em out", and, have their tool bits last as long as possible. They can sell ALL they can produce now, and MORE, but they don't want to expand too much, because, in a drought, they may wind up "machine poor" (over capability vs. reduced demand).
Now, I hope I didn't hurt anyone's feelings, but I've had numerous discussions here with posters who may be too lazy, or not interested enough, to read the information, even when links are provided, but they continue to post the same drivel as though they know of what they speak, or post, whatever.
Now, I'm not the great doo-dah when it comes to metallurgy, OR Cryo processing, but I DO have a natural curiosity and a thirst for knowledge and if there is something I can use that makes my life behind the trigger more rewarding, I'm going to try it, (don't you think gunsmiths in the 16th century, if they'd had the abilities we have today WOULDN'T have tried this, do you honestly believe they wouldn't have?); and I read an article or two in SHNews, too, and tried out the du jour Cryo processor that was all the rage back in the past-mid 90s. And, I didn't notice too much difference in my barrels (when they didn't go to someone else) But the big, BIG thing I DID notice, was that I couldn't get a good straight answer to my questions w/enough peripheral info to fully understand the answer given, and this is why I posted the content of paragraph 6. And that "Pioneer of Cryo" who had patented his process (after he got Rick to teach him the basics, considering the limitations of his machine)? Well, turns out his "process" called for spraying liquid nitrogen into the chamber THREE TIMES during his "Process". He was always threatening to sue people for "patent infringement", even while the patent had "expired", due to "....failure to tender maintenance fees to the patent office."
Now, I have shot numerous barrels that have been properly Cryo processed, and they do seem to run a tad cooler, and are easier to clean, and don't seem to foul as often or as seriously as other barrels in the past. And, some of my friends have found that a fore and aft comparison over a chrono revealed a slight increase in velocity, but also a marked decrease in standard deviation as well as sometimes needing a small boost in charge to return to former levels of accuracy. Now, the interesting idea is, what benefit will meloniting give us? LWRC maintains their melonited barrels have an accuracy life of 25,000 rds.
As is stated in the link to ASM International's site w/the article noted, TIME is of the essence in Cryo processing, and many investigators are now (finally) at the conclusion that, yes, now we KNOW it works, so now lets see how we can "tune" the process to produce the optimum results for various alloys; and what new materials will benefit from this process?
