Don´t think you´ll have much luck finding a good gunsmith in Berlin. Quite a few serious collectors ... but they tend to keep very much to themselves. Even the annual gun show (that doesn´t actually take place annually) is a bit of a let down with a lot of dealers from Poland trying to sell souvenirs dug up and looted from WWI burial sites. But keeping an eagle eye on the Germanicon e-gun web site is worth while.