Obviously, the Chinese had the ability to chrome plate weapons as evidenced by the later chrome plated Norinco Tokarevs imported here.
Chrome plating is a middle of the road deterrent to corrosion, and would be especially useful for the climate of SEA.
It is not outside the realm of possibilty that a higher ranking officer would order such a weapon from the Chinese for private purchase, or have it plated by a local shop.
Regarding the doctrine of "everything belongs to the state," I think you are overlooking the rampant corruption endemic in most Communist states. An officer could get away with an awful lot of things by virtue of his rank.
My tour of duty was Thailand, Laos and Cambodia (which we were never in
), and I have to say that I never saw any chrome plated weapons, but I still wouldn't dismiss it as totally impossible.
I would tend to agree, though that it's far more likely that the GI had it done locally in Vietnam, or possibly when he returned home.
BTW, Ron James,
THANK YOU for your service to your country.