It is a 500NE. Shooting a 470NE gives the same sort of reaction - I thought it was easier (legal-wise) to own a 470 over there.

Are you sure all 50 cals are banned there? Over here in QLD only the 50BMG round is discouraged from private ownership - a 50BMG rifle is in the same licence category as a machine gun, but otherwise there is no calibre limit for rifles (I think). I guess at some point it becomes ordanance though.