It weighs approximately 77 grains if I applied the formula correctly. At 15 feet, that's about 5 grains per foot; probably a T-6 tip. It could be one someone else built and welded tips on, however and that's not unheard of.
From most mfgrs.; wide bands = 5, narrow bands = l.Look at the tip. Does it have a few white bands on it. It's been so long since I used my Versi-tip from Rio I forgot what each band meant.