This rifle was legal for a while in states that required an open primer as the primer was just set on the post under the hammer. It was a standard nipple and then the fire went into the charge like a sidelock. Now they have added a piece over the post that disassembles to take a 209 primer. The whole idea seems a little strange to me and I think they just tried to salvage the main part of the rifle with this add on. Italian stuff is usually pretty good in quality so if this seems like something you could deal with go for it. I believe this is a fair description of how this works. Hopefully someone actually has seen one and can either back up the above or correct it if I do not have it right.