Gentlemen: the Norinco has non standard stock screw bushings, to be sure. Further, there is no Norinco anymore. It was a number of factories banded together under the auspices of the Chineese Government, but no longer exists. I certainly wouldn't use a Norinco for anything other than an anchor.
It is not true, however, that no one makes larger than normal stock screw bushings. Brownells does, as the bushings are often stripped by careless people. Brownells even has the tap required to thread the larger hole, and the drill to make it, if I recall correctly. They certainly do sell the larger stock screw bushings.
Hope this helps. (10mm? sticking finger down throat).
Walt