the home office removed 4 calibres ( i believe ) from the sec 58 creteria and anyone owning these had to hand them in or place on the certicate to keep.
i think you could also apply for a firearms cert if you didnt have one
the closing date was september 24 th or there abouts
i agree its not been well advertised thats why i enquired around march this year and asked for the procedure on what to do.
mine are now listed on my certificate but i cannot ever shoot them and i think they are reclassed as sec 7.3