HSM Ammunition Subsonic 8.6mm Blackout 300 Grain Boat Tail Hollow Point Brass Cased Rifle Ammunition 20 Rounds. 6BLK 300GR SHPBT 20/25 - Specifications for HSM Ammunition Subsonic 8.6mm Blackout 300 Grain Boat Tail Hollow Point Brass Cased Rifle Ammunition: Manufacturer: HSM Ammunition Caliber: 8.6mm Blackout Number of Rounds: 20 Bullet Type: Boat Tail Hollow Point (BTHP) Bullet Weight: 300 grain Cartridge Case Material: Brass Package Contents: HSM Ammunition Subsonic 8.6mm Blackout Boat Tail Hollow Point Brass Cased Rifle Ammunition HSM Ammunition 86BLK1N: Subsonic 8.6mm Blackout Boat Tail Hollow Point Brass Cased Rifle Ammunition 20 Rounds