9mm+P: 115 grains (Velocity: 1125 feet per second)
.40 S&W: 140 grains (Velocity 1120 feet per second)
.45 ACP +P: 185 grains (Velocity 1000 feet per second)
Light bullets shed velocity and thus energy faster, both in the air and in the target. Retained energy aids in penetration of the target. With all else being equal, a heavy bullet will always penetrate deeper than a lighter bullet. Obviously, the 115-grain 9mm bullet is the lightest of the three. The .40 has 122 percent more bullet weight than the 9mm, and the .45 has 161 percent more bullet weight than the 9mm.
9mm+P 115 grains: .355
.40 S&W 140 grains: .400
.45 ACP +P 185 grains: .452
The bigger the bullet, the bigger the hole it makes in the target. The 9mm bullet has the narrowest diameter of the three. The .40 is 113 percent of the diameter of the 9mm, and the .45 bullet is 127 percent of the diameter of the 9mm.
9mm+P 115 grains: 323 foot-pounds
.40 S&W 140 grains: 390 foot-pounds
.45 ACP +P 185 grains: 411 foot-pounds
As velocity increases, so does energy, but at a much faster rate, which can be a bit deceiving. For example, a light bullet going very fast may have more energy than a heavy bullet at moderate velocity, yet the terminal performance of the heavy bullet may be better. That said, energy is still a standard by which a cartridge's performance is measured. The 9mm (in 115-grain +P) has the least energy of the three. The 140-grain .40 S&W has 120 percent of the energy of the 9mm.+P. The 185-grain .45 ACP +P carries 127 percent of the energy of the 9mm+P.
9mm+P 115 grains: 18.5 lb-ft/s
.40 S&W 140 grains: 22.4 lb-ft/s
.45 ACP +P 185 grains: 26.4 lb-ft/s
Many ballistic experts believe that momentum is a better measure for a bullet because it does not have the velocity bias that energy does, and it gives the weight of the bullet more importance than energy. The 115-grain 9mm+P has the least momentum of the three. The 140-grain .40 S&W bullet carries 121 percent more momentum than the 9mm +P. The 185-grain .45 ACP+P bullet has 143 percent more momentum than the 9mm +P.