 It was developed by the Soviet Union as a survival gun for their space program, and was in use from 1987 to 2007, when it was retired due to the fact that the unique ammunition it uses had degraded too far to be reliable.Vierlings ("vierling" being German for "quadruplet") generally consist of two matching smoothbore barrels, a .22 caliber rimfire rifled barrel and a centerfire rifled barrel.Although, they can come in a variety of configurations.