The "anti-jam pin" unscrews, or at least it does in the TA chainrings I use (pin held in place with a small recessed nut on the inner face of the ring). I switched from a standard 5 arm Campag crank ('98 Chorus) to a "hidden arm" crank ('05 Chorus). I drilled a new appropriately-positioned hole in the chainring, used a Dremel to hollow out a small recess for the nut and transferred the pin. That was two years ago. However, I've never dropped the chain off the outside of the chainring, so it may not have been necessary