A (forged) 340 Crank is Not a (forged) 273/318 Crank?

You can have two identical cranks, that weigh the same and they will take different balance corrections. With the same bobweight.

A few degrees difference in where the counterweights are makes a big difference in balance correction.
All of confuses me to no end. That is why I took my crank's to a good machine shop and let them balance them.
Good luck to all and thanks for the info.