Yes, I understood.
I just meant to say that I find such change strange without doing construction changes. And the weight benefit is much less than with the upper cap. I'm not even sure whether such change would yield manufacturing benefits in the case of this simple part. A plastic bottom cap would be cheaper as such but also would need additional cost for preperation for galvanizing.
When you are talking a million units the cost saving to the manufacturer is significant. Brass even back then was a lot more expensive than plastic.Injection molding molds are cheaper in the long haul because there is less wear and maintenance than a stamping die and then subsequent forming die and trim die for a brass base plate. This also requires three steps to make the brass base plate vs one step for injection molding.
Labor is almost always more expensive than raw material,going to a plastic base plate could represent a huge labor savings.
Another consideration is scrap. The cutouts and holes in the brass plate represent scrap material than you do not recover more than 10% of the original cost as raw material.
Where in injection molding there is no scrap as the finished part is molded with all the holes and openings it needs and the gates, sprues, runners to feed the cavity in the mold are ground up and reintroduced to the plastic used for molding.So there is virtually no scrap in injection molding.
both require about the same prep for chrome plating, with the plastic for a chrome body being even cheaper because it could be vacuum metalized in one step vs copper metalized,buffed and painted black for black bodies.
However a brass base plate in black should have been cheaper than chrome but back then they charged extra for black bodies.