They are trying to come out with an entire new group of steel loads which will be capable of use in even older 2 1/2” guns with fiber based wads. Velocity will limit the effective range but with some of the slow burning powders they are getting decent velocities. Either they develop these type loads or an entire group of guns become wall hangers. New guns are being built to use modern steel shells but until now old guns were regulated to lead or Bismuth shells. Bismuth is fairly expensive so they are looking for a cheaper alternative at reasonable pressures.