Given that you live on the coast HD and wind must be a fairly regular condition would it perhaps be easier to do the paperwork on a moderator for a centrefire rifle for 100 yard use? A .223 is pretty cheap to reload and is quiet although my favourite which I use is a 6mm PPC. I have the same issue with wind living high up on the fells...which is why I got rid of my .22 Sako...and whilst I do miss having an easy ability to shoot sub-sonic ammo with no "sonic" crack...the wind actually takes the noise away easily when it is blowing. It is only on quiet still days that the .22 is missed.