Used real fine sandpaper on a wood dowel. Reduced the incidence of jamming greatly.
These rifles are unique and fun to shoot but, alas, mine is inaccurate. Seems to have tight spots in the steel barrel. I don't shoot it much, as 2"+ 20 yard groups just don't do it for me. I may get around to doing something about it, one day... either lap the barrel (some more) or replace it outright.