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Everything You Ever Need to Know About the .40 S&W

Image Via: MidwayUSA

.40 S&W: A Cartridge confused but appreciated.

Whether you know it as .40, Forty Cal, .40 Smith, .40 Auto or just plain old .40 S&W, the .40 Smith and Wesson Cartridge is a cartridge that many would say doesn’t know what it wants to be.

With ballistics like the lighter recoil control of a 10mm Auto, the .40 S&W can fit in to the medium sized 9mm handgun frame. Sitting between the 9mm Luger and .45 ACP, the .40 S&W is a good compromise between both for self defense.


However, .40 S&W is one of those cartridges you either like or you don’t like. Some people enjoy shooting it, others don’t like the snap to the round and it can be hard hitting.


Debuted to the public in January of 1990, and the parent cartridge of the .357 Sig round, the .40 S&W was originally designed as a law enforcement round for the FBI to replace their .38 Special +P load.

After running 9mm and .45 ACP and 10mm through a battery of tests, they found they liked the ballistics and the lower recoil of the 10mm but wanted a cartridge that could fit a 9mm handgun. So the FBI asked Smith and Wesson to design a cartridge around those specs. Hence the .40 S&W was born.

A nice advantage to the .40 S&W is that, with just a simple barrel swap in most cases, you are able to use the same firearm to shoot multiple calibers.

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A great example of that is the Sig Sauer P226. With a simple swap with a factory Sig Barrel, you can go from .357 Sig to .40 S&W. The magazines, springs, everything work with both calibers. The S&W M&P .40 S&W with a barrel and magazine swap will allow you to fire 9mm out of it.

This allows you to do side by side comparisons of different calibers in one firearm. You can practice with cheaper ammo with your actual gun and then carry in your preferred caliber.

Background and Specs

Malis, via via Wikimedia Commons

Using a 10mm projectile in a cut down case, the .40 S&W was able to fit into the medium frame 9mm handgun and push the projectile at pressures that exceed that of .45 ACP.

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At an overall case length of 1.135 in, it is just a little longer then then 9MM Luger. Some have noted that the .40 S&W is almost identical to the .38-40 Winchester. It has the same bullet weight, diameter and muzzle velocity. Bullet weights can vary from 135 -200 gr. Most typical .40 will penetrate from  10-14 inches with an average velocity between 950-1440 feet per second.

Self Defense

The .40 S&W is a great round to consider using for a self defense application. Having the smaller size, you are able to carry more firepower then with a .45 ACP but less then 9mm. Most standard magazines for .40 S&W will hold from 12-16 rounds depending on the design of the firearm.

Availability of the ammo is good and can be found pretty much in any store that sells handguns and handgun ammo. There are also many option for good and reliable firearms available from almost all the major manufacturers like Smith and Wesson, Springfield, Sig Sauer.

Keep in mind that this round was designed for law enforcement use, so this is an excellent round to use. Many of the ammunition manufacturers even offer various types of .40 S&W.

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If you are considering a new self defense round, a great round for competitions or something different to try to shoot, this cartridge is one you should look into. A great balance between size and power presents you with many good opportunities.

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Everything You Ever Need to Know About the .40 S&W