The ASM-DT Morskoy Lev (АСМ-ДТ Морской Лев, sea lion in Russian) is a Russian prototype dual-medium assault rifle.
The ASM-DT was developed from the use of the older APS underwater rifle, where Spetznaz frogmen commented on the APS underwater rifle being horribly inaccurate above water and was not meant to be used in those conditions due to very quick barrel wear. The ASM-DT was designed by Professor Yuri Danilov of TPKTIMash who designed the weapon to be a dual-medium weapon that could perform as well as an AK-74 when used above water and as well as an APS underwater rifle when underwater. Interestingly, the weapon was actually adopted by the Russian army in the early 2000s, but whatever wars it was used in are unknown and unclear due to secrecy.
The ASM-DT is a dual-medium assault rifle with two barrels for different purposes; a smoothbore barrel for use underwater and a rifled barrel for use above water. The rifled barrel has some grooves to expel gases when firing quickly to prevent the barrel from bursting. The rifle has two magazine wells and can accept both magazines at once; the magazine release shifts forward when AK-compatible magazines are used, and its gas system automatically regulates based on the cartridge the weapon is currently firing. Various other accessories were also included, such as a flame arrestor, flash hiders, sound suppressors and even an underbarrel grenade launcher.