The law in N/Ireland states that any weapon capable of firing any projectile "with a rifled barrel" must require the use/need of an F.A.C.
Hence why you can buy a cross bow / long bow etc with no need for an F.A.C. but an air rifle needs one.
The sad fact is that i would imagine that someone, somewhere, will lodge a complaint before it's fully made law here and it will become lost.
UK mainland law, where you need no licence for an air gun under 12ftlbs is a blessing you should all be happy with. Wish we had it here. Save us all some time and money.
I feel for the lads in Scotland faced with the same prospect, ie, an F.A.C for everything.
Takes a while at times to sort the paperwork here for the simplest of deals, then there's the cost, the hassle, and the fact that in England, No distance away, you don't need it at all !
Needing no licence here for an air rifle would be the best deal, but i doubt that day will ever come