I got my FOC over 20% by replacing the 40 gr aluminum inserts with 100 gr brass, in effect a 60 gr increase to the front. But I also replace the 5" vanes with 2" Blazers and use no wraps (I paint the back of the arrow with white lacquer instead). But these are carbon shafts. If I were shooting metal, think I'd go the cap screw way. Some add on weight systems require one to add weight through the back of the arrow; too much messing around (and cost) for reasonable application.