The reality is that the difference between the quality of a standard, mass-produced barrel and a match barrel is getting smaller all the time. Modern techniques for manufacturing barrels have resulted in an amazing level of accuracy and consistantcy that just couldn't be matched 20 years ago. Computer-operated machinery and better metalurgy, as well as a vast pool of knowledge, have all helped to bring the baseline of barrel quality up.
The real key these days is to build in and maintain good QC/QA. That's what makes sure that the 1% (or hopefully less) of parts that had some mistake made to it will be culled out before it makes it onto someone's rifle.
But the fact that a standard, run-of-the-mill chrome-lined machinegun barrel, machined down and installed on a bolt gun, could outshoot other custom target rifles, is pretty amazing.
-Troy