That's interesting. I would imagine you would need precision to the hundredth of the millimeter when making guns? I hung around some people who reloaded brass once and they were using these measuring gauges with that kind of precision.
An AK47, on the other hand, well the whole design is based around very loose tolerances for ease of manufacture and for reliability - not as affected by dirt, mud, sand, etc as other designs.
You do for some types of shooting, but in general no.
And, even if you did, what makes you think that 0.01mm requires modern equipment?
Moreover, tight assembled tolerances don't require tight part manufacturing accuracy. You can hand-fit parts.
http://www.armscollectors.com/darra/darra.htm
and a more recent one: