This is the ‘CARTRIDGE SA BALL GATLING GUN 0.45 inch LIGHT MARK 1’ as described on p. 76 of Labbett for service to India. It used the same 59.5mm case as the standard Mark 1 round, but was loaded with the lighter 410 gr. bullet and 80gr. of powder with a total length of 78mm (3.075in). This was a part of an order of 12 Gatling guns that were manufactured at Elswick for India in 1877. See also image CFMG92(d) in Hoyem Vol 2 p.113