As an observation, when the US originally licensed out the AR-15 to other countries they often also had to license aluminum foundry tech at the same time. We take it for granted now because that tech is old.

The ability to scale advanced or exotic materials science at will was a cornerstone of why US weaponry is difficult to copy. People always underestimate this aspect but it is a major reason why manufacturing of state-of-the-art hardware is not fungible.