- "Conversion kit to use .300 Blackout ammunition. Higher caliber with a lower muzzle velocity, these subsonic rounds pack more energy over greater distances."
- — Description
Compared to the standard M13 magazine, it does not change the ammo count. However, it increases the damage range of the projectiles, as well as removing visible tracers and enemy skulls from the map. As a downside, the bullet velocity and recoil control are reduced.