Mike:
I have not seen reference to Kidderpore in the Walter Locke catalogues or on their gun-barrels, and would assume the Calcutta reference includes that inner suburb.
Just curious: have you seen it listed separately on a trade label or in a catalogue?
My friend (who collects maharajah guns) and I have a bit of a dossier on Indian gun-makers and would be pleased to include this address if possible, with a reference. Hope you can help.

With apologies for the sidetrack.