What is a good subsonic factory ammo in 300 Blackout. I have a 8.5" AR15 pistol in 300 Blackout, no suppressor. I am looking for a good subsonic load that will not go through every wall in my house and down the street into the neighbor's house. Something that is frangible, I think? I recently bought Hornady Subsonic 190 gr Sub-X, have not shot it yet and have no idea if it is the ammo I described above. If there is no such thing as subsonic frangible , please give me info on frangible ammo as well. Any info would be helpful. I don't reload and no plans to start.