Determining age/production period of a mold

[TCLouis]

Trying to determine which of two 429215 molds was made in the mid 60s.

Any clues on determining production date?

[Guesser]

Get a copy of Lyman Reloading Manual Edition 46. On page 152-153 it will list your mold # and when it was listed as a component in which Lyman/Ideal manuals/handbooks. Not exact but it will give you a starting point.
It lists your number as being included in Handbooks #22 thru #40; and then the number was reassigned; whatever that means. #40 was a middle 50's printing, so I don't know about the 60's. Then in Cast Bullet Handbook #1 it lists it as being designed by Ray Thompson as a light weight bullet for 44 Special. Dunno past that.