QB, That mold has a lot of merit and made by an excellent machinist. 
Boring for the brass insert with fixed handles is no small task.
He got the isnert as close to center as possible given the cutout next to the hinge.
The brass insert would be replacable for different size molds. Much easier than than new handles or making new mold blocks.
Mold cavity appears lathe turned with the nose the same diameter as the top of the grooves.
Don't know who did it but admire his work.
Chuck

i just marvel at this level of skilled work, surely done by a master machinist wearing a apron and smoking a pipe. and all the while using manual machines and working out of a gerstner tool box....man do i miss the era!