We recommend that steel shot not be fired through tightly choked barrels, such as a full choked or improved modified choked barrel. Modified choke should be the tightest choke used with steel shot.
Steel shot may create excessive wear to the ramp area of a tightly choked barrel and therefore may damage and ruin the barrel. Note that a more open choke with steel shot does not result in any loss of ballistic efficiency since steel shot patterns tighter than lead shot, and modified choke gives the optimal long range performance with steel shot.
Krieghoff competition shotguns with factory choke tubes can be used with steel shot as long as the choke constriction does not exceed modified. Fixed choked barrels with chokes tighter than modified should ideally be equipped with steel shot suitable choke tubes rather than attempting to have the chokes opened. There are firms in the after market offering choke tube installations. One such firm that specializes in the installation of steel shot suitable choke tubes is Briley in Houston, Texas . They have many years of competent experience and are highly recommended by Krieghoff.