Some of them are, but your right not all and that is the whole point.
They (FEO's) are dealing with a whole book of rules and law, a book with a much broader scope than ballistics and as
@SimpleSimon said "
The HO guidance does say that good reason should not be equated to need, and that they should consider things primarily from the applicant's point of view."
So it's up to the applicant to show to the FLO that there is a 'need' (for that more weighted bullet) rather than a 'want' and that the ground and your firearm handling technique is 'safe'.
As has been pointed out though, the 'guidelines' (from which the FEO is operating) does say that a .22CF is good enough/adequate for Mr Fox so your "need" must outweigh that argument.
It may be easier for the OP to alter his reasoning to more fit the guidelines and the FEO's understanding of the 'need' for such a caliber.
As has been said in this thread already ...
You might be lucky and get an FEO that leans towards being called a 'policeperson' in which case you stand a much better chance of getting a Creed (apparently).