Atomic Rifle Subsonic 223 Rem 77 Gr Hollow Point Boat Tail HPBT. 56 NATO Subsonic Match Grade ammunition features a hollow point boatatil bullet and has low recoil. Specifications for Atomic 00429 Rifle Subsonic 223 Rem 77 Gr Hollow Point Boat Tail (HPBT): Manufacturer: Atomic Ammunition Caliber: .223 Remington Number of Rounds: 50 Bullet Type: Boat Tail Hollow Point (BTHP) Bullet Weight: 77 grain Cartridge Case Material: Brass Muzzle Velocity: 1050 ft/s Application: Target Primer Style: Centerfire What is Atomic 00429 Rifle Subsonic 223 Rem 77 Gr Hollow Point Boat Tail (HPBT) good for? The manufacturer thinks that it is good for target.