A lovely example & a good picture as well, thanks for sharing that.
The search for an effective and efficient method to impart spin to an artillery projectile, dates back at least to 1615, a few early examples are: The elliptical bore, often ascribed to Lancaster, was experimented with in Germany in the 1690s. By 1745 the Swiss had small rifled pieces. In 1774 the Military Society (a committee existing before the formation of the “Board of Officers” which preceded the “Ordnance Select Committee”) experimented with elongated projectiles fired from a smooth bore 6 pr. Even a breech loading gun firing lead coated projectiles had been proposed, by Lieutenant Croly of the 81st Regiment, in 1821, well before Armstrong's design.
Adrian.