I guess mine was the mark III as it had the three pins. Technically I don't think the outer two could be called firing pins as they only prevented the center one from hitting the primer if the shell head didn't have the circular groove for them to fall into. They of course played no part in the firing itself.
Several rimfires, including the Henry, have been made with dual firing pins which both struck the primed area of the rim on opposite sides. Some of these very early rimfire shells didn't get a real uniformity in the priming & this helped insure against misfires.
