It’s difficult to say if the Clinserts are already installed;

If it’s according to Military spec, and the insert is locking, then a coating is done, could be a cadmium coating, or another dry film lubricant.

If a standard insert is used, then usually there is no coating

if it’s a special insert, then the coating is an option:

Can be silver plated, cadmium plated per 3 different norms.

The material of the insert can be also A286, chrome-moly steel, Bronze,….

If it’s for a new project, please specify the size and your wishes and we’ll quote accordingly