Here is the thing - barrel making steel is not really bloody trade secret. Going to any trade shows it is not hard to figure out where or whom to buy steel from.
But, how much can you buy? and how much do you want to pay for it? Is your country embargoed or having problems with export permit for the steel you want to buy?
Next, does your engineers know WHAT to buy and what heat treatment and stress relief need to be for the purpose? Does your shop know how to control the process from deep boring to running that hammer forger?
With KGH, the sales pitch is that A&D boasted to make the "cleanest" CrMoV steel compared to other similar products made by other steel mills. That is kinda half of it, HK probably specifies the heat treatment and stress relieve, that is something they probably will not say too much.
I posted a youtube of an interview with Norinco engineers. The biggest challenge the Chinese claims to encounter in developing precision small arms is the quality of steel as well getting consistent heat treatment and stress relieve results.
The not so deep conclusion is that, you cannot just buy AISI 4140 steel, do QPQ surface hardening on it and claim it to be as good as HK 416 barrel. The graph in the first post shows that, and the Chinese engineers at Norinco pretty much said that out loud.
