Re: Cryogenic treatment
Cryogenic tempering works. By "works" one should ask what exactly does it do for the money? From a microstructure perspective it refines the grain structure and precipitates martensite (hard carbides) without any additional brittleness associated with quenching.
So, what does this buy you? Better toughness, wear resistance and much better crack fatigue resistance (due to smaller, more dense grain structure). The higher the carbon content in the steel the more prononced the results. But it also works with non-ferritic alloys such as aluminum. It appears to me that any alloy that responds to conventional hardening will also positively respond to deep cryogenic tempering.
What won't it buy you? Sub MOA from a poorly fabricated/constructed barrel. I did notice some slightly (though statistically significant) smaller groups at 100 yards, but that was not the reasons I had it done. One would have to shoot, say, 50 rounds of the same lot number prior to and afterwards. I did 20 before and after and the groups were about 20% smaller.
I worked with the gentleman who "perfected" the process (Edward Busch) owner of Cryo-Tech in Hazel Park, Michigan. He and I would sit and discuss metallurgy and he held nothing back from me. He actually offered me a job but I knew it would be a difficult sell since it's the very opposite of what I had been taught so I declined. I will tell you this, however: I saw Tiger Woods' golf clubs (long before I knew of a "tiger woods"), parts of a satellite, cylinder heads for a top aftermarket motorcycle manufacturer tuner, drag race engine blocks and cylinder heads for several top fuel dragster engine builders as well as NASCAR engine components and cylinder heads, AMA motorcycle complete engines and brakes. Cylinder heads, springs, brake discs, connecting rods, pistons and crankshafts are regularly cryo'd in motorsports applications today.
People have misconceptions and this is probably due to them not being very familiar with Metallurgy. A properly done barrel will benefit but will YOU notice it? Probably not. Is it worth the money? To me it is but then I'm well aware of metallurgy and the benefits of grain structure refinement and carbides. Most persons will not be as aware and to be honest I find that most sane persons aren't the least bit interested in wading through dry, technical material. Just keep in mind that it performs NO miracles and MOST of us will not tax our equipment enough to warrant much of the processes available to manufacturers.
Oh, one benefit for barrel makers and firearm manufacturers is that the machinability improves somewhat. The downside is the time required to properly temper and anneal the blanks - and time is money.