Has anyone had any experience with these? As I recall, they're Chinese made.

Yes, I assembled many of them back in the 80s when there was a plethora of Israeli parts kits (US M14). .
Armscorp receivers were not made in China. You are thinking of Norinco or Polytech ones.
I thought they were not the same quality as Springfield armory (the commercial one in Geneseo), but they worked.
There are some very good milled receivers being made now.
Do you have one?