HeymSR20,

"That Greener cape gun is classified as a firearm under English law as it has a rifled barrel. In the UK would be difficult to get a 450/400 on your licence as it is not suitable for deer (not legal because doesn't meet min muzzle velocity requirements of 2,450fps). You could own it but only be allowed to use it overseas."

This is a strange statement, I have no problem at all owning/shooting .577NE, 475 No2 NE but then I use these at Bisley, has the law now changed?