Personal defense weapon
Personal defense weapons (PDWs) are compact magazine-fed automatic firearms, typically performing as a submachine gun designed for secondary defensive use rather than as a primary service weapon. Some PDWs fire a small-caliber (generally less than 8 mm or 0.31 in in bullet diameter), high-velocity centerfire bottleneck cartridge resembling a scaled-down intermediate cartridge, essentially making them an "in-between" hybrid between a submachine gun and a conventional carbine assault rifle.