The Russian special forces dual-medium assault rifles are reportedly slated to enter production next year, according to vpk.name. These rifles use supercavitation to allow for much shorter projectiles that work in both air and water media, which represents a significant advantage vs. older underwater rifle types, such as the ASM-DT. According to the article, the rifles are called “DT”, but the weapon represented in the article’s picture is designated ADS, according to Maxim Popenker’s website. It’s possible the article is referring to a new model of weapon.
Supercavitation works via creating a bubble of gas around an object moving through water, which greatly reduces the considerable drag incurred by moving through dense media, which allows for much higher speeds to be achieved with much shorter projectiles, relative to conventional underwater ammunition.