Tech Cap Material?

I recently acquired a PreWar Tech. It is a bar or 'fat' handle, a Triangular slot base and the typical rounded cap with four corner notches, very similar to a New cap. The razor has had all the finish polished off. It's red everywhere.
I believed these caps to be brass (though the 'faceted' are said to be Zamak). However i found the blade be a bit wavy .. saw some bits of metal flakes causing this and carefully ground them off.. what i see underneath is black or very dark.. clearly not brass.
So... what am i seeing under those flaws which i removed? Is the cap brass or zamak that i've now exposed?
BTW.. the blade is flat now! and a great shave. Not bad for 6 bucks at the antique store.

If you say It's red everywhere then it's brass, red brass which contains more copper. Many caps were made of red brass.

I have also seen some wartime production that looked like normal Techs from the era, but appeared to have zinc alloy caps. I'd want to actually see what we were talking about here before I really could have an opinion, but I definitely don't believe that the faceted caps were Gillette's first foray into zinc.