A Eduard Kettner vierling at auction:

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=331229198












Interesting proof in the final state and what looks to be a 517 plug gauge over 35mm. I don't recall a 517 but there was a 527.





Maybe a script EK near the forend hanger?

Kind Regards,

Raimey
rse