I sort of agree but it's not a case of what you have a right to, but what you require. If you have a genuine reason to own a particular calibre and amount of ammunition you will have no problems. If you just fancy a .223 or whatever because it is cool and you want 3000 rounds for the sake of it (slight poetic license here) then you will have to justify yourself.
Oh, and I would suggest that a .308 is more dangerous than an air rifle, back stop or not
I agree with the above
You do not have the rightto a Firearms Certificate, you have to provide a Good Reason to acquire it an