The "Modified Diana" is buried in Pieper's Gun Lock Patent of Dec. 20, 1892 No. 488,366
https://patents.google.com/patent/US488366A/en

" I adopt the following method of securing (the barrels). I form the cartridge chambers for breech loading in the solid steel block, into the front end of which the barrels are screwed so that their bores coincide with their respective chambers" and are brazed or soldered.

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Leaving no step; steel breech and "Washington" tubes

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The 1895 Montgomery Ward catalog

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1897 Sears

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