I posed the same question to Different, his answer: "August 1994 or shortly thereafter".
I think the Chinese have almost reached the bottom of their pile of M14 parts, receivers in specific.
Agreed!
I live in the states and have easy access to M14 receivers made in the USA.
That said, all of my M14s are built on Norinco & Poly Tech receivers... this has not diminished their value, not at all.
BTW, Chinese receivers are dimensionally closer to USGI receivers than all others except SEI.