as jersey isnt part of the european union, and we dont have european firearms permits (available to eu people to make it easier for travel inside the eu), when i have been boar shooting in france i needed the invitation (similar to what you need in sa and now namibia i think) from the people i was hunting with to show customs to clear my rifles. it was a few years ago but it was the easiest import into a country ever, they looked at the invitation and waved us through took about 1 minute!!. dont know about entering and storing though, maybe book a days hunting and then it will be easy. just a thought. also they have regulations on bringing military calibres in so check on that. i think people can have military calibres but only as members of a club and for target shooting not hunting,so for example rifles any where else chambered in say .223 will for france be chambered in .222. or .308 will be 7mm-08.