According to Nigel Brown's "British Gunmakers" , this serial number was used by Rigby between 1830-1835. Long before the 410 existed, much less cartridges.
Ron Gabriel in his " American & British 410 Shotguns" makes no mention of Rigby as a maker of 410 shotguns.
Take a look at the bell of the barrels here. Looks amazing like the crescent photo posted above.
Rigby would never allow this glaring miss fit to leave the shop.
As to the "12 King Street" address on the barrels:
Rigby was indeed on King Street;
In 1931 J W C Barratt (formerly of J Barratt & Son of 6 Mitre Street, Aldgate) managed the Sackville Street shop, he was still with the company in 1955 when the shop moved to
32 King Street, St James's.
In 1984 J Roberts & Son (Gunmakers) Ltd bought the company and in 1985 moved it to their premises at
5 King Street, Covent Garden
However, the only gunmaker I can find at "12 King Street" was
George Mason;
George Mason, son of John of Sydney Street, Stepney, he was recorded in business at 128 High Street, Whitechapel in 1837. He was next recorded in 1840 at
12 King Street, Commercial Road when he became a freeman of the Gunmakers Company.
Pete
