It appears to me the Beattie gun linked by Dan does not have the firing pins actually attached to the hammers. This gun has a stud on the hammers which retract the pins but the hammer still Hits them in falling.
On the Tolley the pins are actually pinned to the hammers. One would assume the hole in the Flat portion which fits the hammer has to be slotted as the hammer travels in an arc rather than a straight line. Much like the rammer on a Colt 1860 revolver.
My personal belief is this would be a less efficient arrangement for firing a gun than the normal arrangement of the hammer hitting the firing pin. I will have to say though it is a very nice looking gun & one I would be proud to own just for its uniqueness.
