Indeed a great looking old Clabrough. My Clabrough is marked J P Clabrough & Bros & is from the 1890s @ SN 4230. It has 28" Damascus barrels, choke in both barrels. It has 2 5/8" chambers & a Doll's Head rather than a Cross Bolt. Hardly any finish left, either case colors or bluing, but with low pressure 1 oz loads it is one fine quail, woodcock etc gun.
I have seen some of the history of these guns but forget now just when Johnson became a part of the company. As I recall he was the US importer in California.