Like many great inventions throughout history it was accidental. I got both molds and took them apart and gave them my usual cleaning, assembled one and put on handles, placed it in the mold oven on the hot plate while the pot heated up. Fluxed and started casting dropping them on a towel. After 4-5 pours I look down at the bullets and . . . . .
What the ????? Yep, had put together a half from the GC mold with a half from the PB mold. Yep, amazing halves from two different molds fit together that closely, on some you couldn't even see the parting line.