Handguns

The FBI adopted the 10mm Auto in 1989 for its service round. The 10mm was really the Bren Ten cartridge that dated back to about 1983, but the loads the FBI selected for its pistols were quite a bit milder than the hot Bren Ten. And it didn't take the folks at Smith & Wesson long to realize that they could equal the performance of the FBI load out of a smaller cartridge case.

Enter the .40 Smith & Wesson. About 0.140 inch shorter than the 10mm Auto (but otherwise nearly identical), the .40 S&W was compatible with the frame size of some 9mm pistols--unlike the 10mm. The .40 S&W had lots more punch than the 9mm Parabellum and immediately took off as a primary gun for police officers and anyone else interested in serious self-defense.

This cartridge has become so popular that everything you need for reloading is easily available. In theory, you could shorten 10mm cases to make .40s, but .40 cases are so easy to come by that there's not much point in going to any extra work. Besides, 10mm cases use the large pistol primer while the .40 uses the small primer size.

There isn't much magic to loading for the .40 S&W. While we have included loads for bullets up to 200 grains, the very heavy projectiles do create a bit of a problem. The overall length of the completed round must be held to no more than 1.135 inches, or magazine feeding problems will arise.

When the very heavy bullets (which are necessarily long) are seated to meet this overall length limit, the body of the bullet intrudes so deeply into the case that there isn't much room left for powder. That means that the heavy bullet performance suffers in two ways. The velocity drops simply because the bullet is heavier and also because it is being driven from a "smaller" case. Bullets between 165 and 180 grains seem to be about the best choice for the .40 S&W. Some pistols are very fussy about the nose shape of bullets, and you may have to experiment to see what brand will feed well in your gun.

When it was first introduced in 1990, the .40 S&W got a reputation for being difficult to reload to produce accurate results. That's pretty much a bum rap--although reloaders have found that the cartridge seems to do best with powders that come near to filling the case. That means that the very fast powders (with the resulting small charge weights) should be avoided if accuracy is a primary consideration.

There's another factor in powder selection that comes into play with the .40 S&W. It's called "bulk density." With some powders, especially the ball powders, the case volume required to hold a given weight of powder is less than that required for the same weight of a lighter and fluffier powder.

That means that while you might have room in the .40 S&W case for as much as 8.5 grains of one kind of powder, you might only fit in 6 grains of a less dense powder. What that means is that the less-dense powder needs to have a faster burning rate to get up to the desired working pressure, and velocity may suffer a little. The best powders for the .40 S&W will be found right in the middle of the burning rate list for pistol powders. There's no shortage of good choices.

When it was first introduced in 1990, the .40 S&W got a reputation for being difficult to reload to produce accurate results. That's pretty much a bum rap--although reloaders have found that the cartridge seems to do best with powders that come near to filling the case. That means that the very fast powders (with the resulting small charge weights) should be avoided if accuracy is a primary consideration.

When loading for autos, as opposed to revolvers, there's another item to keep in mind. All pistols seem to have a minimum power level that they need to function properly. That level varies from caliber to caliber, from one pistol make and model to another and even from one specific gun to another. Still, there is a simple way to compute a number that will be close. Simply multiply the weight of the bullet in grains times the muzzle velocity in feet per second. For our test gun, a Smith & Wesson SW40VE, the minimum power level was about 135,000 units. Our starting loads were selected to provide this power level. There's also a maximum power that a given pistol will take without starting to beat itself apart. In our tests that level was about 200,000 units, and our peak loads are all under that figure.

The reloader will find that it's pretty easy to reproduce the .40's factory performance levels. The SAAMI maximum average pressure level is 35,000 psi--that's taken by the piezo (electronic) method. Because this is a relatively new cartridge, there is no copper crusher (CUP) level specified.

The .40 S&W is a wonderful compromise. It's enough cartridge to get the self-defense or police job done and is chambered in guns compact enough for comfortable carry.