I thought someone more knowledgeable than I would post something but here goes..... I drug out my Madis Winchester book.
There is very little written on the subject I quote from page 97 of his book: "In shape and appearance, early firing pins were made exactly as on the Henry Rifle. Between numbers 24,000 and 26,000 the firing pins were less pointed in an effort to aid ignition, but soon the old pattern was again adopted. The rimfire '66 was made with twin wedge-shaped firing pins to the end of the model's production".