This .510 diameter 570 grain Safari Solid hunting bullet is designed for the Nitro Express double rifles. Design incorporates 3 + 1 band configuration for reduced barrel strain. It has the 67% Meplat BBW#13 nose profile which has proven to give the deepest penetration of any bullet tested to date. Technical Info: Caliber: .510 Weight: 570 grains Required Twist Rate: STANDARD G1 Ballistic Coefficient: .200 G7 Ballistic Coefficient: OAL: 1.448 Projection Length: .700