Vanguard Outfitters Subsonic 5.7x28mm 55 Grain FMJ Brass Rifle Ammo 25 Round. 7x28 rounds using 55 grain projectile. These are specifically designed to be subsonic from pistol only. Specifications for Vanguard Outfitters Subsonic 5.7x28mm 55 Grain FMJ Brass Rifle Ammunition: Manufacturer: Vanguard Outfitters Caliber: 5.7x28mm Number of Rounds: 25 Bullet Type: Full Metal Jacket (FMJ) Bullet Weight: 55 grain Cartridge Case Material: Brass Application: General Features of Vanguard Outfitters Subsonic 5.7x28mm 55 Grain FMJ Brass Rifle Ammunition EXCEPTIONAL QUALITY 5.7x28 ammunition Virgin Brass and New Components only. The coatings utilized are proprietary and involve combinations of preparation steps coatings and application methods. They are for our exclusive use only. Application - civilian commercial rounds Technical Information Package Contents: Vanguard Outfitters Subsonic 5.7x28mm 55 Grain FMJ Brass Rifle Ammunition What is Vanguard Outfitters Subsonic 5.7x28mm 55 Grain FMJ Brass Rifle Ammunition good for? The manufacturer says that it is best for general.Vanguard Outfitters VGSub: Subsonic 5.7x28mm 55 Grain FMJ Brass Rifle Ammo 25 Round