This gun is a rare example of a Jackson design for a method of speeding up combustion in percussion guns by directing the fire from the cap straight into the centre of the breech block. I haven’t yet found a patent, nor do I know if one exists for this design. Given that the patent breech by Henry Nock added a secondary chamber in order to speed up ignition by setting up a small primary explosion to set off the main charge, its not clear that going straight into the breech would actually achieve what Jackson intended. One can see why he might have thought it would, because Nock’s design is counter intuitive. i look forward to trying it out – I wonder if an ordinary video camera is fast enough to capture small differences in ignition speed – I rather doubt it. Judging purely by the style, the wood and the engraving I would put this latish in the percussion era – very probably post 1840.