Just a word of caution...
I don't know how platinum hardness compares to gold, and I think Dan may be referring to this when he states the, "Platinum formed into them". The point is that gold liners, and I suspect platinum were swedged into place rather than threaded in. The metal being too soft for fine threads to hold up to the pressure; not to mention that a gold threaded liner would probably not survive the instillation process
Jeff