I'm glad you caught that.
And .46ACP, you didn't lose a couple of us. I was trying to keep up. I have very little firearm knowledge, minus the shooting experience. I know more in practice, than background. Point is, I do enjoy the in depth explanations. It's good to learn.
Simplified for those of us who are not as familiar with this stuff, it all boils down to how you determine the impact force of the bullet. There's basically two sides to this one: Light and fast vs. Heavy and slow.
Joe Velocity says kinetic energy is expressed as 1/2 mass x velocity
2 and uses that formula for impact force of a bullet.
Bob Diameter says the area of impact has an effect on the force transmitted to the target, and expresses that as mass x velocity x diameter.
They fight like fishwives over this stuff. I will give a few examples:
Joe Velocity says:
A 180 grain (a measure of the mass of the bullet) 10mm Auto bullet fired with a muzzle velocity (the speed the bullet leaves the gun) of 1030 feet per second will yield 425 foot pounds (a measure of force) at the muzzle. Light and fast.
A 230gr .45ACP bullet with a muzzle velocity of 900fps will leave the barrel with 415ftlb of force. Heavy and slow. Win for Joe right?
Bob Diameter counters with:
The 180gr 10mm bullet has a diameter of .400" so the impact energy (expressed in Taylor Knock Out Factor, which accounts for bullet diameter) is 10.6
The 230gr .45ACP bullet is bigger by .050" , and has a TKO of 13.4. Win for Bob right?
So you can see, it depends on what particular factor of bullet performance you consider most important. High velocity rounds travel flatter trajectories with less drift, while larger slower bullets have a large area of impact on the target and transfer more of their momentum. The key is to find a round that offers a good balance of both.