AutoCAD Inventor :: Removing Characters From IProperty

I'd like to build a rule into my standard part template that takes the part number (which it automatically gets from the file name by default), removes the characters after a delimiter, as well as the delimiter itself, and sets that as a new custom property. For example, we'll call the custom property Prop1

For part 123-321-1.ipt

Inventor already sets part number iProperty to 123-321-1

I want to set Prop1 to 123-321

For part 123-321-25.ipt

Inventor already sets part number iProperty to 123-321-25

I want to set Prop1 to 123-321