If you go to the link I provided, the plating is brass.
I see it! I seem to remember something about the manufacturing process article saying the molds were sprayed with a brass/wax dust before the lead was poured. It didn’t result in an actual full coating because the lead would mix with the dust. The result was a brass/lead coating they gave the name Yellow Jackets to.
Funny how I can remember something so far back but can’t remember the reason I stood up 10 minutes ago ...... to go to the restroom or get more coffee? So I sat down again. The chair’s not wet yet and I do have a bottle of water here, so I guess all’s OK.