SIG 300BLK subsonic rounds are propellant chemistry optimized to produce the ideal amount of down-bore pressure for cycling both piston and gas driven platforms, with or without sound suppression. Engineered with the SIG MCX™ mission configurable rifle in mind - these rounds minimize recoil, sound, and muzzle flash while maximizing the number of shots on target.
SIG SAUER subsonic rounds feature a 220gr Sierra Match King Projectile for superior accuracy and minimal dispersion when suppressed.
Every round was above subsonic speeds with my 10 inch barrel. They looked to be well made rounds, but I wanted subsonic rounds to test my new silencer that I just got approved for. I used my magnetospeed v3 to get the velocity of the rounds. It doesn't matter how good they look if they are shooting above subsonic speeds.
Cycles perfectly in my Seekins NXP8 pistol, and is accurate in both the NXP8 and my Ruger American Ranch Rifle bolt gun. Stays subsonic with the 16in Ruger barrel. Tight groups. This ammo is consistently excellent.