This bullet is designed to function at subsonic speeds and put game on the ground quickly and quietly. This makes it an excellent choice for .300 Blackout and .300 Whisper rifles. A minimum impact velocity of 900fps is required for the hollow point to function as intended. Instead of mushrooming, Cutting Edge's subsonic Raptor bullet sheds 4 large blades after about 1-2"" of penetration while the base continues. It is manufactured out of solid copper bar stock on a CNC Swiss style lathe. SPECS Caliber: .308 Weight: 190 Grains Required Twist Rate: 1:8" or Faster OAL: 1.467" Projection Length: Blackout: .859", Whisper: .7 Mfg: Cutting Edge Bullets