i install several dozen scopes every year. There are a lot of cheap made in China bases and rings on them market. Some of the Weaver rings are made in China. All of the Simmons rings are made in China. Some of the Leupold rings are made in China and they are trash too.
The made in China rings are notorious for being out of alignment: Out of alignment rings can ruin your scope. i will not install them: It takes too much time with a honing bar to straighten them up.