Just to clarify what I'm saying say you get a 308 for deer and then someone offers you a lovely 223 at silly money. You would then need to put in a variation (£45), wait x number of months then find out he sold it to someone else.
I can't see a reason not to have that slot on your ticket from the start tbh.
Thanks, this is exactly what I'm hoping to avoid, get the right calibres in at the start as much as possible and minimise interactions because they seem to be a hassle too often.