I purchased this knife recently. I am trying to confirm that it's handles are black jigged delrin and not black jigged bone. They definitely have a delrin like feel. Also, its the tang stamp was used from 1946-1973. Any ideas on a more exact manufacture date? The blades both appear to be polished on both sides. I have read older catalogs mentioning polish on one side of main only and there is a BF thread going into detail about this.