blindeye....I found your 446188 in Ideal catalog 14 (1902) and 15 (1903).  I don't have #16, but by catalog 17 (1906) it is missing from the catalog along with the 446109, 110 and 187.  Don't have catalogs earlier than #14 so it may have been listed earlier.

Lyman began a separate "special list molds" in catalog 28 (1927,28,29) and the 446109,110 and 187 were on that list but no 446188.

The mold could have been made even though it is not in the catalog.

It should use a 188 top punch, but good luck finding that.  The 187 or 186 nose is similar but not exact.

The description in both catalogs is the same as the Cast Bullet Handbook.

Does your mold have permanent handles or is it a separate mold?

max