I still can't pull up the photos,so I'm still in the dark.Over time I have seen that Dave and Sharps give good advice.As Sharps opined, a chambercast is going to be required to ID the caliber, even then it may be unclear. Sluging the barrel to find the dia at the muzzle may also be helpful. Coln A/Rh means Coln(Cologne)Am(on the)Rhine(river).
Mike

Last edited by Der Ami; 07/21/15 10:54 AM.