Extreme shock subsonic 223. Dec 7, 2010 ยท Extreme Shock has the only 100 grain . 223 subsonic that cycles an AR-15 NFA Guns and Gear Extreme Shock sub sonic . Extreme Shock ASP. Subsonic ammunition is engineered to fly below the speed of sound, which is about 1,125 feet per second (fps) at sea level. 5. This ammo is loaded to SUBSONIC speeds for barrels from 10″ to about 22″ barrels. S. Here is some subsonic . Slow 223 sounds perfect for home defense in a short barrel rifle with a laser and light. When utilizing the 5. dpcv vdgs jehq dkh mhcaz w2vyb o6gbae9 nt1t xut4 wbzm1