Hi Jim Watson
I feel like an intruder here as I know absolutely nothing about firearms.
What's a Rolling Block ?
My rifle had a breech that covered the whole end of the barrel and had an hexagon shape matching the barrel and finishing as a ball or so, but I can't remember if there was a firing pin through the breech or anything else to fire the bullet. But It was in no way close to the picture PetahW shows here.
The breech had an ear on the same side the hammer has it. You would bring that ear backwards, in fact turning it on the pin that retains it in place, load the bullet in the chamber, push the ear back, cock the hammer and fire. And then you can feel the empty case and the breech flying right over your head or so.