Not at all uncommon to see some HJ steel buckles which have for example a primary copper coating, first applied in order to better accept (good adherence without lifting), the final nickle silver plating.
Here are some images of a HJ where the obverse is totally devoid of the once applied nickle plate and instead, the "golden" copper coating remains.
Hello David! Cool! Here's my Paul Cramer M4/44 HJ - and you can see the brass just peeking out from the wear on the buckle....