The guy I have gotten Gators from in the past (Blammer on Cast Boolits) lists .41 cal “Lyman Thin” type, max shank diameter .397 and .416 (.416 Rifle normally” at max shank .393. Other molds I have looked at/considered show the shank at .391-.393 also.
Struggling with some .475 boolits right now that shanks are a bit small on so don’t want to go down that road. If we can work this out I’ll be in for on of these in Brass for sure, flipping coin between 2 or 4 cavity.