5.56 62GR Bone Frog Ammunition® FMJ-BT (B556FMJ62)5. 56 62GR Bone Frog Ammunition FMJ BT (B556FMJ62) We pumped up the volume on our 55GR practice round to achieve the same feel and accuracy of our 62GR Solid Copper Hollow Point, in a full metal jacket round. Built with high quality powder, primers, and US made brass, this 62GR FMJ round features the same muzzle velocity and tight tolerance as our BFA SCHP. Train like you've never trained before. Manufactured exclusively for Bone Frog Ammunition Las