Norc pistols are made of tougher, stronger steel than their American counterparts. They use the fact that they make their own machines, tools, and cheap labour to produce decent pistols. If I was building a custom 1911, i'd start with a norinco frame and slide.
For what it's worth, I've been shooting 5.1gr 231 with a lee 255gr rnfp. It's a big boomin load and the pistol takes it like a champ.