Finaly I can be for some use here in the forum.. let me just enjoy the moment for a while..
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Ok, the answer is quite simple.
Any rifle or pistol produced before or within the year 1870 is concidered antique. Therefore they can freely be sold and imported without lisence.
If the rifle is a pre 1870 model but produced recently, it is not concidered antique. (I recently checked this, because I was drooling over a black powder rifle from a fellow forum member)
If it's a post 1870 firearm, it is quite easy for he/she to import it, as long as he have the necessary papers. After the gun application is signed by the local police, one copy needs to go to customs prior to import. In addition, the seller should claim a copy as well.