 The development of <unk> powder , based on <unk> or <unk> , by the French inventor Paul <unk> in 1884 was a further step allowing smaller charges of propellant with longer barrels . The guns of the pre @-@ <unk> battleships of the 1890s tended to be smaller in calibre compared to the ships of the 1880s , most often 12 in ( 305 mm ) , but progressively grew in length of barrel , making use of improved <unk> to gain greater muzzle velocity . 
