Ultramax 8.6mm Blackout 300 grain Subsonic Rifle Ammo 20 Rounds. 6 300GR HPBTM 20/10 - Specifications for Ultramax 8.6mm Blackout 300 grain Subsonic Rifle Ammunition: Manufacturer: Ultramax Caliber: 8.6mm Blackout Number of Rounds: 20 Bullet Weight: 300 grain Application: Hunting Target Package Type: Box Primer Style: Centerfire Package Contents: Ultramax 8.6mm Blackout 300 grain Subsonic Rifle Ammunition What is Ultramax 8.6mm Blackout 300 grain Subsonic Rifle Ammunition good for? The manufacturer suggests that it is suitable for target hunting.Ultramax ULT-86BLK-1-N: 8.6mm Blackout 300 grain Subsonic Rifle Ammo 20 Rounds