Developed in the USSR in the 1970’s by Vladimir Simonov, the APS was created in response to the ever increasing threat from enemy Frogmen or Combat Divers. It is a fully-automatic, gas operated rifle that was designed to be effective underwater, and to a lesser degree, above water as well.
Up until that time, a knife was the only source of defence against enemy divers. The SPP-1 Underwater Pistol was adopted in 1971, but proved only useful in close combat and was poor at engaging targets at a distance.
The APS was adopted in 1975 and was the primary weapon of Soviet Combat Divers. It fired 5 inch steel darts through a smooth bore and delivered these darts in full-auto with very effective ballistics. The APS magazine held 26 darts fitted into a casing similar to the 55.6x45mm, though the caliber of the rifle is officially listed as 55.6×39 MPS.
Issues arose because of the very limited above-water life span that the APS had. In the water the APS could fire roughly 2000 rounds before major malfunction. Above water that figure dropped to as low as 180. While this bore little issue with Soviet Combat Divers, it was a major complaint of the Spetznaz soldiers who fought in both environments. This drove research to develop a rifle that carried with it the same reliability and functionality either in or out of the water.
The APS remained in service up until 2000 when it was replaced by the ASM-DT which solved many of the problems with its ability to fire and carry two different calibers simultaneously; one for the water, and one for land. The ASM-DT provided the modularity and effectiveness that the special forces needed while at the same time providing the same characteristics with the Combat Divers.