thats f****d up, my FEO conciders eg: .38/357 to a .22 as definately a one for one " slot for slot " free of charge, & never had a visit on both occassions..
the first time i called them to change a calibre for a calibre i was expecting a charge, when i called them they said its no problem & just sent in your paper work for a one for one, never heard of the saying before they told me this..
mind you, my lot also class a fox as vermin,as you say "yet another misinterpretation of the rules by different regions!"
rich