A complete and total waste of time and money, at least in so far as the claims made by the cryo treatment fans where rifle performance is concerned. They don't shoot any more accurately after being treated, the don't foul any less (or even any differently) than an untreated barrel, and they don't last a bit longer than an untreated barrel. I ran a blind test of this many years ago with three Hart barrels from the same production run, chambered identically with the same reamer, and fired a with a control series of ten 10-round groups through each barrel after they were broken in. All of the ammo for this (and the subsequent control groups) were from the same lot of bullets, powder, cases and primers. After the baseline accuracy was established, two of the three barrels were sent out to two different cryo treatment firms by our plant engineer. When they returned, all three of the barrels were refired using the same series of ten, 10-round control groups. There was virtually no change in any of the barrels. A fourth barrel was added here, but was visibly different and hence not a part of the true "blind" test. This was one of the Blackstar barrels someone has previouly mentioned. They'd heard about the series I was running and wanted their barrel included in the testing. I obliged, and ran this one with the three Harts, giving it the same sort of eval. The point was to establish the baseline accuracy, before and after cryo treating, and to revisit this same evaluation every 1,000 rounds until the barrels were shot out. Once they were pulled from active testing, the identity of the cryo'ed barrels would be revealed. To make a long story short (the full article was published in Precision Shooting Magazine), we spent over 17,000 rounds through these four barrels, and saw virtually no difference in barrel life, accuracy, fouling . . . or anything else for that matter. All four barrels quit shooting at about the 3,500-4,000 round mark, which was perfectly typical for Hart's chambered for the 308 Winchester for our purposes (I had to have consistent sub-1/2 MOA 10-round groups, without fail). In short, no gain whatsoever.
Cryo treatment is used in a number of industries, and I have no doubt that it works well for those industries. I've heard several gunsmiths say that barrel blanks that have been cryo treated seem to machine easier, and I don't doubt that. However, I don't belive that the process can do anything to resist the type of erosion we see in rifle barrels, affect accuracy or fouling. As I said, machining and/or machinability is another matter entirely, and I'll leave that call to others.
