8×139

8×139 is a fictional caliber designation. It does not correspond to any known or widely adopted ammunition type in military, sporting, or historical firearms contexts. Caliber designations typically consist of a bullet diameter followed by the cartridge case length, both measured in millimeters. For example, a 7.62x39mm cartridge features a 7.62mm diameter bullet and a 39mm long case. The combination of 8mm and 139mm does not align with any established firearms development or production. While it is possible for enthusiasts or designers to create custom or experimental rounds, 8×139 has not gained any significant traction or recognition within the firearm community. It is likely a hypothetical designation or a misunderstanding of existing caliber nomenclature. Without any documented firearms chambered for this specific round or its widespread use, detailed specifications, performance characteristics, or historical context are unavailable. Its existence remains within the realm of theoretical or non-standardized ammunition.