Oddly enough while looking I found this old post from where?
Here is another site posting
This site lists American gun manufacturers.
From what I can find it looks like Golcher was a lock manufacturer and apparently made only a few rifles and pistols. He did however provide locks to a lot of other manufacturers both here and abroad. I see his name on the picture you provided on the lock is it anywhere on the barrel?
I found this site and it might be where you could get the information you are looking for. He will need detailed pictures of all aspects of the gun, but he may be able to give you some answers
Hope this helps somemore