A good 70 bore six shot gas-seal single-action revolver by Joseph Lang

A good 70 bore six shot gas-seal single-action revolver by Joseph Lang, sighted octagonal barrel 5 in., top flat engraved 'J. LANG, 22 COCKSPUR ST. LONDON', London Company view and proof marks; cylinder with numbered chambers and further view and proof marks, nipples inclined from the vertical and set within oval wells, reciprocating upon the arbor pin at the moment of firing to close the cylinder/barrel gap; steel action engraved with foliate scrolls, off centre hammer with long thumb spur; one-piece chequered wooden grip, engraved steel butt cap with a trap for percussion caps; presented in an associated fitted case with accessories including a fluted copper powder flask, a rammer with concealed worm, bullet moulds, an oiler, and other items; trade label for the Army and Navy Co-Operative Society. By way of this interesting design, in the words of John Deane "the orifice of the chambers is widened, so as to permit the posterior orifice of the barrel to set into them, and thereby prevent the escape of flash and gases" (quoted in Taylerson, Andrews and Frith, 'The Revolver 1818-1865')