when smokeless powder started being used to load shotgun shells in the place of black-powder. As smokeless powder did not have to be loaded in the same volume as black-powder to achieve the same power, being more powerful, the volumes of wads had to increase, to fill the shotgun shell enough to permit proper crimps still to be made. Initially, this meant that increased numbers of over powder card wads had to be stacked to achieve the same stack-up length. Eventually, this also led to the introduction of one-piece plastic wads in the late 1950s through the early 1960s, to add additional wad volumes, in order to maintain the same overall shotgun shell length. Dram equivalence has no bearing on the reloading of shotgun shells with smokeless powder; loading a shotgun shell with an equivalent dram weight of smokeless powder would cause a shotgun to explode. It only has an equivalence in the reloading of shotgun shells with black powder. See also Gauges 2 bore 4 bore 6 bore 8 bore 20-gauge shotgun .410 bore Breaching round Lead shot Snake shot Red rocket, a 3D printed shotgun slug as a politically motivated demonstration of its possibility Shotgun slug Shrapnel shell Rifle cartridge References External links zh-yue:霰彈 Paramilitary cartridges Shotgun shells