what would these tapered rods be used for?

The look to be about the right size and taper for a boss in a diecast part. Perhaps they were used for inspecting the release taper of the mold cavity that makes the boss? Thee rods are too long for a cavity, but they are often through, with another part blocking the bottom and carrying the pin that will make the screwhole.

Joe Gwinn

well, that is possible, but I think unlikely - I think these came from HRL, which was a research laboratory, though they could also have come from one of the manufacturing parts of old Hughes Aircraft - but to my knowledge nothing was cast on site

I work in defense, and we do have things diecast. Often, we insist on owning the tooling, to avoid lock-in, and to support the typical 20 to 30 year lifetimes required by the DoD.

Joe Gwinn