18 lb. lead core has the best sink rate. A radius rod tip is a big help( twily tip). A Willis knot is best for attaching backing and/or leader. To tie a willis knot, remove about 8" of lead from lead core, slide leader up into core where lead was removed, and tie two or three overhand knots equally spaced on the core thereby trapping the leader inside the overhand knots. This cushions the leader and prevents breakage. 27 lb. core might be better for kings