Correct British War Department marked bullet moulds are very hard to find so I was fortunate to acquire this. The British War Department purchased Beaumont Adams revolvers in both 38 and 54 bore from around 1856. The earliest revolvers were supplied though the firm of Deane, Adams & Deane so the type became known in the military as Deane's revolvers. This is an early War Department and broad arrow marked 54 bore bullet mould supplied by Robert Adams. Note the tailed bullet which was more commonly seen on the earlier Adams 1851 pattern self cocking revolvers. 

Note the similarity in the engraved War Department W^D marking on the bullet mould and the Beaumont Adams revolver. They could have both come from the same hand.