A lot depends on how you intend going out to France.
If you via the Tunnel then expect trouble!
Customs are VERY HOT which is not surprising, conscidering the confinement of the Euro star.
Are you going on Hoiliday?
Do you have a house out there?

I have taken firearms out with little bother but then I have an F.A.C.& European F.A.C.

With Firearms basically you MUST inform the ferry operators that you intend taking a gun out to France.
leave plenty of time to get themselves organised!
They will take it off you and return it to you when you dock French side.
Problem you are going to have is you don't have a bit of paper registering it to you?
Not unless it's FAC rated then you should not have any trouble.
They are bound to ask why you want to take an air rifle out there?
You should also know you are not aloud to shoot fur or Feather with ANY AIR GUN!
Personally! forget it, I think it could get Messy? <img src="http://jsramsbottom.co.uk/bbs/e/icon_frown.gif" alt="Frown" width="15" height="15"><!--graemlin:-->