Cartridge of the Week, the .40 Caliber Smith & Wesson, .40 SW

By CTD Allen published on in Ammunition, Firearms

Few cartridges can have an iconic tag. What is rarer is when experts call a cartridge iconic when still in its infancy. Twenty years is just an infancy when it comes to the world of cartridges. Of all the ones we have reviewed, this is the baby of the bunch. However, the baby has achieved as close to perfection as perfection can be. Perfection is the .40 Smith & Wesson.

The .40 Smith and Wesson

A little lesson in physics. Don’t run for cover—we will make it very simple. The ultimate goal of a cartridge is to launch a bullet with enough energy to give us the desired result. For target practice, that is accuracy as well as precision. The two are not the same. That discussion is for another time and for target shooters, when the goal is repeat performance. Whereas, for those who are shooting something other than paper – getting the most bang for your buck- then Kinetic Energy is what we need to know a little more about.

Kinetic Energy – It is that simple

Kinetic Energy is the result of half the mass times the velocity squared or K=1/2MV². Let us make it even simpler. The weight of the bullet is the mass; how fast it goes is the velocity. That means if you have a 100-grain bullet you will only be able to use half of the weight in the formula thus M=50. However, with velocity, it is the square of the feet per second. Therefore, 1000 fps becomes 1000×1000=1,000,000 and V=1,000,000. Thus Kinetic Energy is K=50×1,000,000. With a little more math, we can arrive at the foot pounds of energy, but I will spare you that for now, as our brains are hurting.

It should be simple; the faster the bullet, the better, right? Here in lies the rub. Fast things tend to go through things and continue onward. When a bullet passes through the intended target, it has wasted its potential energy and is free to hit other non-intended targets. So, a big slow bullet is the best as all energy expends into the target. Not so fast now, as penetration is essential in bullets to cause internal damage to the target for the quickest incapacitation possible.

9mm vs 45 ACP. Velocity vs Mass

Now we arrive at the century-old argument of 9mm versus the .45 ACP. Is it the little and fast, or the big and relatively slow? During the late 1980s, several civilian law enforcement encounters rendered revolvers obsolete. This was due in part to to the lack of firepower and ammunition capacity. Furthermore, the 9mm, in its U.S. civilian infancy, had the firepower but lacked the stopping power required to end shootouts as soon as possible. Please spare me the hate mail;I know there really is no true knock-down power. Nevertheless, when a mule kicks you may not go down, but you will probably have some trouble while making those follow-up shots. However, big .45s lack the firepower and penetration of the 9mm.

.40 Smith and Wesson

The FBI sent manufactures back to the drawing board. There was a brief courtship with the 10mm but it didn’t last through the honeymoon. The 10mm was close, but it required too much gun for the average law enforcement officer to carry. In June 1989, a joint venture between Winchester and Smith & Wesson went to work to find that perfect balance of weight, mass, firepower, and consistent energy transfer. The new cartridge had to boast some big thump in a reasonable package.

This was a monumental task for this R&D group, which a Mr. Bersett oversaw at Winchester and a Mr. Melvin at Smith & Wesson. However, the result changed civilian law enforcement side arms across the country. The result was the .40 Caliber Smith & Wesson or the .40 S&W. We have a cartridge that can launch a 185-grain bullet, a lighter .45 ACP, at speeds close to that of the 9mm, over 1,000 feet per second.

Glock 22 .40 S&W

The next task and one still in progress is to design a weapon that can contain this mighty mouse. All internet hype aside, the Glock craze has enveloped this cartridge and with the Glock 22 in .40 S&W, it has become the weapon of Choice of the majority of all police agencies for their patrol officer. Smith & Wesson makes an equally good weapon in the M&P 40. It would be hard to choose between these two firearms.

The truth is that the majority of our story about this cartridge has yet to be written as it goes through it growing pains. Nevertheless, in my humble opinion, it is the best out there at this time. No other current caliber possess the best blend of mass, velocity, and thus energy transfer as the .40 Smith and Wesson. Now I just need some Christmas money to get one!

Small but Effective

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