The Winchester Invector-Plus interchangeable choke tube system works hand-in-hand with back-boring to offer consistent, dense shot patterns with just the constriction needed for the shooting situation. The longer choke taper inside an Invector-Plus choke tube produces consistent patterns with more uniform densities and fewer fliers. Invector-Plus eliminates gases slipping between the choke tube and barrel that could damage the choke tube and the barrel.