A 12.7x55mm PS12B special cartridge with an 18 gram subsonic armor-piercing bullet with a heat-strengthened steel core with a two-layer semi-jacket, a lead interior and a bimetallic exterior, in a brass case. This cartridge was designed in the early 2010s to provide the ASh-12 assault rifle with capabilities to neutralize hostile personnel equipped with basic and intermediate ballistic body protection, in addition to providing a significant stopping power effect due to its caliber and being able to inflict substantial adverse effects on the target after impact. However, due to its design, it has a high probability of bouncing off various surfaces.