Ultramax .300 AAC Blackout 208 grain Tipped Subsonic Rifle Ammo 20 Rounds. 300 AAC Blackout 208 grain Tipped Subsonic Rifle Ammunition: Manufacturer: Ultramax Caliber: .300 AAC Blackout Number of Rounds: 20 Bullet Weight: 208 grain Package Contents: Ultramax .300 AAC Blackout 208 grain Tipped Subsonic Rifle Ammunition Ultramax ULT-300BLK-1-N: .300 AAC Blackout 208 grain Tipped Subsonic Rifle Ammo 20 Rounds