If it's a genuine one for one, that being a straight swap, for example a .243 for a .243, then there's no cost. If you want to add or swap to a different calibre or have, in effect a new slot, then it's £20.
The thinking behind it being that there's no difference in a one for one as regards reason for having it and it's a paper exercise in effect, whereas with a new calibre, they would look at that.
I want to swap a 243 to a 6.5 creedmoor ..
CorrectSorry but you're not quite right there Pedro.
One for one is free regardless of whether there is a change of calibre or not. It is only if you increase the number of firearms (moderators count as firearms) that a variation fee is payable.
lf l sell “any“ of my Firearms it’s a free variation if my variation application is done within 7 days of sale date, variation any other time it’s £20.
Include a short letter with the form, explaining what you want them to do.part 12 of the form 201 says , If you wish to dispose of any firearms currently shown on you firearms cert please give details ....
im not disposing , just deleing , is it the same just put 243 .
only it asks for type , make , serial number