I have never seen a monobloc British barrel, nor damascus tubes (3 Iron 'British Best') joined to damascus breech. Is the maker R. Grove?

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\[Linked Image from photos.smugmug.com]

The proof marks date to 1875-1887 and H. Pieper's patent (using a steel breech) was 1881. The initial patent had the tubes inserted from the breech with a step from breech to barrels.
Pieper Modified Diana (no step and "Washington" tubes inserted from the front) with steel breech

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