I recently bought a Lyman 429422 (hollowbase) mold at auction, and I'm trying to get an idea of it's age. I know it's really old. This is, of course, the 44 Keith hollowbase, nose pour mold, and does have the mold blocks separate from the handles. The big difference is that the hollowbase plug isn't the wooden handled type, but is held rather loosely in place by a screw, similar to what you might expect to see from Cramer. My plug is not reversible by the way. The blocks are not vented, as you might expect. It has the correct period handles, and looks exactly like the mold shown in the 1929 Lyman catalog pictures on castpics.

For un-vented mould blocks, I'm going to assume that it was stamped "Ideal". Your mould probably dates to the 1930s.

The HB plug could be an after-market modification. I've seen that done before (after the original HB plug presumably got lost).

http://www.lasc.us/Fryxell_Book_Appendix_A_MouldAge.htm

Ideal. I've also had Ideal HBWC molds with this type of hollowbase plug, and have seen an early 32 HB mold from the one-piece era that uses the same type of base plug. I'm currently resisting purchasing the 32 mold since I try not to buy molds for collection purposes. I actually prefer this early style to the later wooden handled types.

ETA: there are also no holes in the bottom of the mold to indicate that it ever had the other style plug setup.