White areas on 1900s
 

Anyone know if the bottom of the extension rails on 1900s are supposed to be in the white? How about the inside of the extension near the chamber which is exposed above the breechblock?

Your verbal descriptions are ambiguous...not because you intended them that way, but just because word descriptions are subject to interpretation. Please post photos of the areas you are questioning. Based on what I think you are asking, yes they should be in the white.