Hello Krakov,
There are no grooves or lands in a Lancaster oval bore barrel. they're as smooth as a baby's bottom or have a mirror like finish just like a high quality shotgun has.
Most fouling from Black Powder gets blown out of the barrel and leading is virtually non-existant as there are no reamer or rifling cutter marks (tool chatter) to scrape lead off the bullets as they pass up the barrel.
Provided whoever shot the rifle in the past, cleaned it correctly after use, there should be no pitting from Chlorate primer residue or BP fouling. There isn't any other design of barrel that is as easy to clean as a Lancaster Oval Bore Rifle.
Harry
