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Forensic Ballistics · Tools
Compute muzzle energy, momentum, energy density and sectional density from bullet mass, velocity and diameter.
E = ½mv², p = mv
Projectile
1 grain = 0.06480 g. A 124 gr bullet is 8.03 g.
1 ft/s = 0.3048 m/s.
Used for sectional density and energy density.
Muzzle energy
518.4J
E = 1/2 m v^2 = 0.5 x 0.00800 kg x (360 m/s)^2 = 518.4 J
Energy alone does not predict wounding. Bullet construction, expansion, yaw and the tissue struck matter as much as the number.
Muzzle energy is a starting point, not a wounding assessment. Terminal effect depends on bullet design, deformation, path through tissue and intervening barriers. Velocity should come from a chronograph, not a published figure, since barrel length and load change it substantially.
Kinetic energy scales with the square of velocity but only linearly with mass, which is why a light fast bullet can carry more energy than a heavy slow one. Momentum, being linear in both, ranks them differently, and the two figures answer different questions.
Energy density, energy divided by the frontal area of the bullet, is often more informative than energy alone when comparing how readily a projectile will penetrate.