The .410 bore (often known as .410 gauge) is a shotgun cartridge. It is the second-smallest gauge of shotgun shell commonly available, beaten by the very obscure .360 CF cartridge.
Design Details[]
The .410 bore has similar base dimensions to the .45 Colt revolver cartridge, though the .410 is significantly longer, up to 3 inches (76 mm). This allows some revolvers (such as the Taurus Judge series of revolvers) and derringers chambered for the .45 Colt to accept .410 without modification.