yes up from the bottom but only the small section of rib thats between the plugs . At least the two I originally looked at did .
I had ask Bill about this a couple times and he had also stated that he had seen much the same .
i also have some photos of a Frenchy that has button type breech plugs . IE the standing breech is held to the barrels by button screws that thread into the back of the breech . originally tried to purchase this piece but the owner wanted way , WAY more then it was worth IMO .
As you can see , it wasn’t as high end piece . But I sure would have liked it for patterns
I think the next one i build will be an over and under double flint