While cleaning parts for the five CHs we are redoing, noticed some of the lense clips are brass. I mentioned this in our thread about CH Disassembly/Assembly Line - en Masse and figure I would bring this up separately hoping for an answer.
Brass clips are on the left.

Steel clip on left is identical to the brass clip on right.

Is there a time frame when the brass clips were used? Pre-WWII?
The brass clips came from doors that were on the type "D" lights. Have noticed some similar clips that came from a "DT" had rounded corners.
Cheers!