WaA103 Hi-power
 

I have a tangent sighted WaA103 ser# 68xxx in beautiful shape w/2original mags + an orig.41 dated holster. Here's my question. The inside of frame is straw colored, is this from the original bluing process not going to full blue? I and several other collectors have never seen this. Any clues appreciated. The exterior finish and markings are original. Thanks, Dan