It is a shop and a gunmaker since 1820:

http://www.wertgarner.at/ws/frontend/seite/SeiteAnzeigen.php?seite=ueberuns

and of course they have the knowledge to restaure your gun, see example:

http://www.wertgarner.at/ws/frontend/partner/PartnerShop.php?arId=a00000035&intWarengruppeId=407

But I think, you will get this knowledge in the U.S. of America as well, as Mike said.
Especially if you think on transport and costs, the european solution should be second choice...

Cheers,
Gunwolf