In the grand tradition of starting out the most complex and rapidly
working to the simplest method, the idea is to buy a #41 HSS drill
blank, round the point, then mill a slight flat on one side. Then turn a
collar that extends up into the wooden handle, this collar will have a
set screw so I can lock in the pin.

After seeing the old style locking pin (uses pin on collar against pin
in block, under the screw head), it looks like it will be a positive
stop. The new system uses an e-clip where its difficult to see the
opening when re-inserting the pin.

My hollow point molds have mild steel pins, takes a good enough
polish. Either smoke or cold blue them before use. Any polishing
marks should go lengthwise. You don't need an exotic alloy, there's
no strength involved here, the pin just takes up space and needs to
come out easily. Just make sure you allow enough draft when you make
the thing. I've made enough of them from hardware store hot-rolled
shafting. If I were doing it now, wooden knobs would be a problem
since my major supplier went out of business a few years ago. Factory
jobbies have a hole drilled in knob+pin and a drive pin shot in from
the side to hold the works together. Most of the time it works. Have
had a few loosen up.

Stan