since9
Campaign Veteran
There's a lot of different ways to rack and stack a bullet's effectiveness, ranging from the laws of physics to compiling statistics based on morgue reports. The problem with using the latter is that they don't include the ones who lived.
As for physics, there's more to the picture than the bullet's KE (1/2*m*v^2). There's also kinetic momentum (m*v) as well as both of those divided by the caliber (known precisely) or the expanded diameter (varies from round to round). Finally, one must consider the mean length of penetration (also varies from round to round).
Axioms:
1. Kinetic Energy is proportional to the amount of damage that will be done. This results primarily in shock caused by rapid loss of blood and blood pressure. Keep in mind, however, this only includes the portion of the body through which the bullet travels. If you have a highly penetrating bullet, much of that kinetic energy will be lost.
2. Kinetic Momentum is a rough indicator of the amount of impact the target will feel. This results primarily in the wallop that is felt, mostly via CNS effects. This, too, only effects the body so long as it's in the body.
3. Both KE and KM are important, as both are important to "stopping power," but in different ways.
4. A simple, yet workable means of comparing the "stopping power" between different rounds is to simply multiply KE and KM together, then take their square root.
Over the years I've gathered data on many rounds, and have compiled the following table, sorted on this value of stopping power (KME-root). Please note the results for the .357 rounds vary considerable, while the values for the .45 rounds fall into a fairly narrow range, the same as the values for the 9mm. The primary reason for the narrow range has to do with the operation of the the semi-auto. Revolvers, on the other handle anything down to firing just the primer.
You'll notice the .357 round with the most stopping power is just 9.54% greater than the .45 round with the most stopping power, at least by this simple formula, of course. And don't forget, if it penetrates the body, this "stopping power" result is significantly diminished.
Cartridge (Wb@MV) KME-root
.380 ACP (90 at 1000) 22.3
9mm Makarov (95 at 975) 22.6
.38 Spec. (125 at 850) 24.3
.38 Spec. (140 at 800) 24.8
.38 Spec. (158 at 760) 25.9
.38 Spec. +P (110 at 1000) 27.2
.38 Spec. +P (125 at 950) 28.7
.38 Spec. +P (158 at 890) 32.8
9mm Luger (115 at 1135) 34.4
.357 Mag. (140 at 1000) 34.7
9mm Luger (124 at 1100) 35.4
9mm Luger (147 at 990) 35.9
9mm Win JHP (147 at 990) 35.9
9mm Win Bonded PDX1 (147 at 1000) 36.4
9mm Luger (115 at 1180) 36.5
9mm Win Silvertip HP (147 at 1010) 36.9
.44 Spec. (240 at 750) 38.6
9mm Win Silvertip HP (115 at 1225) 38.6
9mm Win JHP (115 at 1225) 38.6
9mm Luger (124 at 1181) 39.4
.357 Mag. (110 at 1300) 40.4
.40 S&W (180 at 950) 41.3
.357 Mag. (125 at 1235) 42.5
.38 Super Auto +P (125 at 1240) 42.7
.38 Super (125 at 1240) 42.7
.40 S&W (135 at 1190) 43.4
.45 ACP (230 at 850) 44.6
.45 ACP (185 at 1000) 45.8
.45 ACP (200 at 975) 47.7
.45 Colt (250 at 860) 48.5
.357 SIG (125 at 1350) 48.5
.40 S&W (155 at 1180) 49.2
.45 Colt (200 at 1000) 49.5
.44 Rem. Mag. (200 at 1000) 49.5
.45 Colt (225 at 960) 52.4
.357 Mag. (125 at 1450) 54.0
.357 Mag. (158 at 1250) 54.7
10mm Auto (180 at 1150) 55.0
10mm Auto (155 at 1300) 56.9
.357 Mag. (180 at 1180) 57.1
.357 Mag. (140 at 1400) 57.4
.44 Rem. Mag. (240 at 1144) 72.7
.44 Rem. Mag. (200 at 1295) 73.0
.44 Rem. Mag. (240 at 1172) 75.4
.41 Rem. Mag. (210 at 1300) 77.1
.44 Rem. Mag. (240 at 1200) 78.1
.44 Rem. Mag. (300 at 1150) 91.6
.44 Rem. Mag. (265 at 1300) 97.2
.44 Rem. Mag. (225 at 1450) 97.3
Bottom line: For maximum stopping power, pick the round that will stay in the body and has the largest KME-root.
As for physics, there's more to the picture than the bullet's KE (1/2*m*v^2). There's also kinetic momentum (m*v) as well as both of those divided by the caliber (known precisely) or the expanded diameter (varies from round to round). Finally, one must consider the mean length of penetration (also varies from round to round).
Axioms:
1. Kinetic Energy is proportional to the amount of damage that will be done. This results primarily in shock caused by rapid loss of blood and blood pressure. Keep in mind, however, this only includes the portion of the body through which the bullet travels. If you have a highly penetrating bullet, much of that kinetic energy will be lost.
2. Kinetic Momentum is a rough indicator of the amount of impact the target will feel. This results primarily in the wallop that is felt, mostly via CNS effects. This, too, only effects the body so long as it's in the body.
3. Both KE and KM are important, as both are important to "stopping power," but in different ways.
4. A simple, yet workable means of comparing the "stopping power" between different rounds is to simply multiply KE and KM together, then take their square root.
Over the years I've gathered data on many rounds, and have compiled the following table, sorted on this value of stopping power (KME-root). Please note the results for the .357 rounds vary considerable, while the values for the .45 rounds fall into a fairly narrow range, the same as the values for the 9mm. The primary reason for the narrow range has to do with the operation of the the semi-auto. Revolvers, on the other handle anything down to firing just the primer.
You'll notice the .357 round with the most stopping power is just 9.54% greater than the .45 round with the most stopping power, at least by this simple formula, of course. And don't forget, if it penetrates the body, this "stopping power" result is significantly diminished.
Cartridge (Wb@MV) KME-root
.380 ACP (90 at 1000) 22.3
9mm Makarov (95 at 975) 22.6
.38 Spec. (125 at 850) 24.3
.38 Spec. (140 at 800) 24.8
.38 Spec. (158 at 760) 25.9
.38 Spec. +P (110 at 1000) 27.2
.38 Spec. +P (125 at 950) 28.7
.38 Spec. +P (158 at 890) 32.8
9mm Luger (115 at 1135) 34.4
.357 Mag. (140 at 1000) 34.7
9mm Luger (124 at 1100) 35.4
9mm Luger (147 at 990) 35.9
9mm Win JHP (147 at 990) 35.9
9mm Win Bonded PDX1 (147 at 1000) 36.4
9mm Luger (115 at 1180) 36.5
9mm Win Silvertip HP (147 at 1010) 36.9
.44 Spec. (240 at 750) 38.6
9mm Win Silvertip HP (115 at 1225) 38.6
9mm Win JHP (115 at 1225) 38.6
9mm Luger (124 at 1181) 39.4
.357 Mag. (110 at 1300) 40.4
.40 S&W (180 at 950) 41.3
.357 Mag. (125 at 1235) 42.5
.38 Super Auto +P (125 at 1240) 42.7
.38 Super (125 at 1240) 42.7
.40 S&W (135 at 1190) 43.4
.45 ACP (230 at 850) 44.6
.45 ACP (185 at 1000) 45.8
.45 ACP (200 at 975) 47.7
.45 Colt (250 at 860) 48.5
.357 SIG (125 at 1350) 48.5
.40 S&W (155 at 1180) 49.2
.45 Colt (200 at 1000) 49.5
.44 Rem. Mag. (200 at 1000) 49.5
.45 Colt (225 at 960) 52.4
.357 Mag. (125 at 1450) 54.0
.357 Mag. (158 at 1250) 54.7
10mm Auto (180 at 1150) 55.0
10mm Auto (155 at 1300) 56.9
.357 Mag. (180 at 1180) 57.1
.357 Mag. (140 at 1400) 57.4
.44 Rem. Mag. (240 at 1144) 72.7
.44 Rem. Mag. (200 at 1295) 73.0
.44 Rem. Mag. (240 at 1172) 75.4
.41 Rem. Mag. (210 at 1300) 77.1
.44 Rem. Mag. (240 at 1200) 78.1
.44 Rem. Mag. (300 at 1150) 91.6
.44 Rem. Mag. (265 at 1300) 97.2
.44 Rem. Mag. (225 at 1450) 97.3
Bottom line: For maximum stopping power, pick the round that will stay in the body and has the largest KME-root.