...a longer seal and a longer bolt probe-to-striker pin to cock it. However, many riser breeches and risers come with the items. You will not need a new barrel band as the metal breeches have a set screw to retain the barrel in place. you will need a new front end plug, or you can trim the existing one down.
"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."