thanks marakai to clarify this

one question "Not commonly encountered these days, but BSA and others (including Westley Richards?!!) built single-shot centrefire rifles using Lee Enfield actions."

if they had use a Lee Enfield action just out of the production line or maybe out of the scrap box ( because the action failed military imspection for a lesser problem but was actually safe) there would be an opening in the bottom for the magazine. what had they done with this to close it?