Interesting subject. The Momentum vs. Kinetic energy theories.
Momentum has an emphasis on mass...a la the .45 at a moderate velocity(830-900 fps). 185-200 gr JHP being the most effective in this range.
Kinetic has the emphasis on higher velocity a la the 9mm. The 115 gr JHP at 1300-1500 fps has been the standard, although the FBI tried to up the weight and get closer to the Momentum side with the 147 gr JHP at a sub-sonic velocity(950 fps).
The 10mm was a total step in combining the two., high velocity(1300 fps) and bullet mass and weight(.40 caliber/200 gr JHP)
Problem with the 10mm was it battered the guns badly. So, the FBI went to the 10mm Lite. A toned down velocity(900 FPS). This left a large amount of the case empty and a possible detonation might occur.
In steps S&W with a modified 10mm cartridge....small primered, 200 gr JHP, moderate velocity, substaintial crosssection(.40 cal) and POOF!! the 40 S&W is born.
Now, having said all that, it comes down to which portion of the stopping power curve you want to be on. Recoil plays a key role in this. You certainly want to have control of the weapon...9mm being fairly easy to handle is still adequate for defense. The 125 gr 357 Magnum is sited as the best for stopping power, but you pay in recoil.
FORGET ABOUT 1-SHOT STOPPING POWER. There is no such thing as it takes a brain or spine shot to effect a complete shutdown of a perp, both iffy under stress. Proper bullet placement and 'hit them til they go down' no matter the caliber should be how you train.
"FORGET ABOUT 1-SHOT STOPPING POWER. There is no such thing as it takes a brain or spine shot to effect a complete shutdown of a perp, both iffy under stress. Proper bullet placement and 'hit them til they go down' no matter the caliber should be how you train." Oh, I am not so sure of that:
From my limited shooting of this little number, it has "near-one-shot" stopping power on the fellow who launches the rounds.
I don't think the guy at the other end would be in any shape to 'continue' if hit anywhere near a vital organ...
--Boris