No 40 Short & Weak I've ever fired, regardless of the weapon or the cartridge, has ever come close to double the recoil of a 9MM. In fact, the recoil is strikingly similar, not surprising given how close they are ballistically.
The average 40 Short & Weak load fired by law enforcement is a 150 grain bullet at just barely over 1000 feet per second (muzzle energy 350 foot pounds).
By comparison, the average 9MM load fired by law enforcement is a 125 grain bullet at around 1100 feet per second (muzzle energy 330 foot pounds).
You'll note a muzzle energy difference of less than 20 foot pounds, about 350 and about 330. The 9MM tends to run to the high side of that velocity, often around 1150 feet per second.
Very little difference.
The 40 Short & Weak and the 9MM are most often found in guns built on the same frame, and even the cartridge size is very similar. Usually, the 40 Short & Weak has one or two less rounds, the frame of the gun is the same, only the barrel and magazine are really different. Often even the recoil springs are the same, meaning the power of the cartridge transfered to the slide and frame is VERY similar.
There is only 0.045" difference in bore size. In fact, the 40 Short & Weak was developed by Smith & Wesson because the FBI felt that the 10MM standard load of a 180 grain bullet at 1200 feet per second was too likely to over penetrate and generated too much recoil. They requested that Smith & Wesson develop a 10MM or 40 caliber cartridge that was very similar in size and power to the 9MM, so as to fit the same weapons with high capacity magazines and small enough grips to acomodate most anyone.
In truth, the 40 Short & Weak was developed mostly in response to the "Miami Shootout" where Jerry Dove's 9MM Silvertip failed to stop one of two bank and armored car robbers Michael Platt who managed to kill Dove and his partner Ben Grogan, and critically wound several other agents. The sad fact is, the 40 Short & Weak nearly duplicates the performance of the 9MM round that "failed".
By comparison the 45 ACP 230 grain at around 900 feet per second is around 410 foot pounds, but felt recoil is not TERRIBLY increased.
The 10MM with a 180 grain bullet at around 1200 feet per second easily exceeds 550 foot pounds, but is not nearly so manageable for the less serious shooter. You can also use a 155 grain bullet at 1350 feet per second for around 630 foot pounds.
The 357 Magnum round we carried was a 125 grain bullet at around 1650 feet per second, it was a +P round, rated number one in one shot stops, with the 230 grain 45 ACP a close second. The muzzle energy is a whopping 750 foot pounds!
The reason the 45 ACP scores so close to the 357 Magnum, despite the 350 foot pound difference in muzzle energy, is the 45 starts out 0.100" bigger in diameter, and the hollow cavity expands quickly to a far larger slug than the 126 grain 357 Magnum.
The 357 was not nearly so bad as it was suggested, even the women easily managed the recoil of the Smith & Wesson 686 Distinguished Combat Magnum we were issued. A couple of well under 130# women actually qualified with a score of around 90%.
Believe it or not, the 44 Magnum (my favorite revolver, but not my favorite carry gun) hasn't scored quite so well in the one shot stop category. The 180 grain bullet at 1650 feet per second scores nearly 1100 foot pounds of muzzle energy. That is rated as the number 2 round for the 44 Magnum. Number one is a 210 Silvertip at around 1350 feet per second, it only scores 850 foot pounds of muzzle energy. Evidently, unless used against body armor (the two lower levels are not rated to stop a 180 grain 44 Magnum) the 180 grain load is too hot. Last I looked, the 44 Magnum was around #5 on the one shot stop list percentage wise.
Needless to say, my personal choices for carry guns include a 45 ACP, a 357 Magnum, a 44 Special, and a 45 Colt. While the 9MM and the 40 Short & Weak might be okay, I prefer a more powerful round rather than a larger magazine. Between 5 and 7 rounds is about enough to cover all I've ever seen used in a personal defense incident, usually with plenty to spare. In a situation a law enforcement officer could possibly find himself (or herself) in, where a high volume firefight MIGHT happen as a one in a million encounters, I'd still rather have 5-7 shots of a more powerful round between reloads and simply carry one or two more magazines or speed loaders.
