Compared: The .357 Magnum and .40 S&W
By Chuck Hawks
These two cartridges are outstanding for self-defense and have also been used by many police departments. In addition, the .357 Magnum is often chosen for protection against both two and four-legged predators in the field. Typical bullet weights for the .357 Magnum range from about 110 grains to 200 grains and for the .40 S&W from 135 to 180 grains. The .357 Mag. is chambered in a wide variety of revolvers, while the .40 S&W is available in a wide variety of autoloading pistols.
Introduced by Smith & Wesson in 1935, the .357 Magnum was the original magnum revolver cartridge. It was based on a lengthened and strengthened .38 Special case loaded to higher pressure. For this reason, any .357 Magnum revolver can also safely fire all .38 Special and .38 Special +P ammunition. The .357 is one of the all-time best selling handgun cartridges, widely used for both hunting and personal defense. It has also been adapted to rifles.
The .357 Magnum has become the standard of comparison among personal defense handgun cartridges, with the highest percentage of one shot stops of any handgun cartridge. Almost every revolver that can stand the pressure is chambered for the .357 Magnum and there is an equally large selection of factory loaded .357 Magnum ammunition. Virtually all ammunition manufacturers load .357 Magnum cartridges. There are small frame, medium frame and large frame .357 revolvers. It is also one of the most popular calibers in single shot pistols and even some autoloading pistols have been adapted to the cartridge, making for an extensive choice of guns in the caliber.
The .357 Magnum's cartridge dimensions are as follows: rim diameter = .440", head diameter = 0.379", mouth OD = 0.379", case length = 1.290", bullet diameter = 0.357", cartridge overall length = 1.590", Maximum average pressure (MAP) = 35,000 psi.
For most of its life, the standard .357 Magnum factory load has driven a 158 grain bullet of .357" diameter at a muzzle velocity (MV) of 1550 fps from an 8-3/8" barrel (Remington figures). Because the .357 was loaded to full pressure, this velocity figure was pretty close and was verified by independent chronograph tests, including mine. In this, the age of the tort lawyer, the SAAMI maximum average pressure (MAP) of the .357 Magnum has been reduced to 35,000 psi. The factory loaded 158 grain bullet now has a catalog MV of approximately 1250 fps and muzzle energy (ME) of 548 ft. lbs. from a 4" vented test barrel.
.357 Magnum reloaders have a huge choice of suitable bullets and powders. According to the Hornady reloading manual, reloaders can drive 158 grain bullets at up to 1400 fps and 180 grain bullets at 1150 fps from an 8" revolver barrel within current SAAMI pressure limits. Most .357 revolvers are highly accurate, an advantage over the great majority of autoloading pistols and especially .40 S&W pistols, which generally have a reputation for indifferent accuracy.
The .40 S&W is one of the great success stories among modern cartridges for autoloading pistols. It was designed by Winchester and introduced in 1990. The FBI had adopted the 10mm Auto cartridge, only to find than too many FBI agents could not handle the recoil in the S&W pistol the Agency had chosen for their new service autoloader. Also, the pistol's grip size was uncomfortably large for agents with small hands, especially female agents. Consequently, the FBI's Firearms Training Unit developed a reduced power 10mm Auto load often referred to as the "10mm Lite." This used a 180 grain bullet at a MV of 980 fps and met the FBI's requirements for bullet expansion and penetration.
The light load did not need the big 10mm case to hold its reduced powder charge, so Winchester developed the shorter .40 S&W at that company's request. The shorter cartridge could then be chambered in smaller, 9mm size pistols, an advantage for shooters with small hands and for concealed carry. Here are the .40's dimensions: rim and head diameter = 0.424", mouth OD = 0.423", case length = 0.850", bullet diameter = 0.400", cartridge overall length = 1.260", MAP = 35,000 psi.
Due to its limited case capacity, bullets in the 135-165 grain range are probably most suitable in the .40 S&W for civilian self-defense, although factory loads are commonly offered with bullets up to 180 grains and that bullet weight remains popular with the FBI, police and many civilian .40 S&W shooters. Typical 155 grain factory loads achieve a MV around 1180 fps from a 4" test barrel, while typical 180 grain factory loads achieve MV's around 980 fps. According to the Hornady reloading manual, with maximum loads, the .40 S&W can achieve MV's of 1300 fps with 155 grain bullets and 1100 fps with 180 grain bullets.
Following the .40's adoption by the FBI, many U.S. police departments and civilians followed suit and today the .40 S&W is among our most popular handgun cartridges. Both ammunition and pistols are very widely distributed and commonly discounted.
We will use Hornady Custom factory loads in each caliber for this comparison. These are not maximum performance loads for either caliber, being well below the top loads shown in the Hornady Handbook of Cartridge Reloading. However, they are typical of both .40 S&W and .357 Mag. factory loads from the major U.S. manufacturers.
To represent the .357 Magnum, we will use the 158 grain XTP-JHP factory load. To represent the .40 S&W, we will use the 155 grain XTP-JHP factory load. We will compare these factory loads in velocity, energy, trajectory, sectional density, bullet diameter and recoil.
Velocity is important for initiating bullet expansion and it is the most important factor in calculating kinetic energy. Higher velocity flattens trajectory, making hitting easier at extended ranges and particularly at unknown ranges in the field. Here are the published velocities in feet per second (fps) of our comparison loads at the muzzle, 50 yards and 100 yards.
The .357 Magnum shows a clear advantage in velocity at all ranges, ranging from 70 fps at the muzzle to 93 fps at 100 yards.
Kinetic energy is defined as the ability to do work. In this case, the "work" involved is primarily powering bullet penetration and expansion. Both are, of course, necessary for lethality. It is also worth noting that kinetic energy is also reasonably good indicator of potential killing power when comparing similar cartridges shooting similar bullets. Here are the energy figures in foot-pounds (ft. lbs.) for our comparison loads at the muzzle (ME), 50 yards and 100 yards.
The .357 clearly has a sizeable advantage in energy over the .40 at all ranges. This bodes well for its killing power, particularly for use in the field against four-legged predators or for hunting CXP2 game.
Velocity and ballistic coefficient (BC) are the factors that primarily determine a bullet's trajectory. Sometimes the need for personal defense occurs at greater distances than anticipated. Seven yards or less may be the statistical average, but sometimes bad guys do not play by the rules and bring slug shooting shotguns, rifles or magnum revolvers to gunfights. In such circumstances, the need to reach out and touch someone makes a flat trajectory important. The flatter the trajectory, the easier it is to hit the target as the range increases. This particularly applies to those who carry a handgun for protection in the field against two-legged predators when camping, fishing or hiking. Trajectory is even more important for a hunting handgun and many .357 revolvers also serve as hunting tools.
For purposes of comparison, we will assume the common 25 yard zero distance. Here are the approximate trajectories for our comparison loads from 25 yards to 100 yards.
As you can see from these numbers, the .357 Mag. shoots flatter than the .40 S&W. This is due to both its higher velocity and the superior BC of its bullet.
Sectional Density is the ratio of a bullet's weight (in pounds) to its diameter squared (in inches). SD is important when comparing cartridges and loads because, other factors (such as impact velocity and bullet expansion) being equal, the bullet with the greatest SD will penetrate deeper, creating a longer wound cavity and increasing tissue destruction. Obviously, however, if the bullet penetrates all the way through the target, wounding ceases. Superior SD also improves the penetration of barrier materials, giving the bullet a better chance to reach a target on the other side (other factors being equal). The actual bullet diameter of the .357 Magnum is .357" and the actual bullet diameter of the .40 S&W is .400"
The .357/158 grain bullet has a clear advantage in SD over the .40/155 grain bullet. This means that the .357 should provide superior penetration.
Bullet diameter determines cross-sectional area. Given an equal percentage of bullet expansion, a larger diameter bullet will create a wider wound cavity, destroying more tissue. Bullet diameter and SD tend to cancel each other, superior diameter creating a wider bullet track and superior SD a longer bullet track, other factors being equal. Here are the actual bullet diameters of our two cartridges.
The .40 S&W has a clear advantage over the .357 Mag. in bullet diameter and cross-sectional area. It should produce a wider wound channel.
Recoil is a bad thing, as it distracts the shooter, leads to flinching and degrades accuracy. Anyone can shoot better with a pistol that kicks less.
Probably the most popular .40 S&W service pistol is the Glock 22. The G22 weighs approximately 2.13 pounds with a loaded magazine. It is hard to say what is the most popular, full size .357 revolver, but the Ruger Blackhawk with a 6.5" barrel must be right up there. The Blackhawk weighs 3.0 pounds. These are the gun weights we will use when calculating the recoil of our comparison loads.
Surprisingly, the .357 actually kicks less than the .40 S&W in our test guns. However, in guns of identical weight the .357 would kick a bit harder than the .40 S&W. Both cartridges generate rather sharp recoil compared to guns of similar weight shooting .38 Special +P or 9x19mm cartridges. .40 S&W guns can ONLY shoot .40 S&W ammunition, but all .357 revolvers can also shoot .38 Special cartridges. This gives the .357 a big advantage in reduced recoil for target shooting and practice sessions.
Summary and Conclusion
The .357 Magnum beats the .40 S&W in every performance category except bullet diameter. A .357 Magnum revolver is also more versatile than any .40 S&W pistol, because it can handle a wider range of bullet weights and loads, including all .38 Special ammunition. .38 Special factory loads are less expensive than .357 Magnum or .40 S&W ammo, substantially reducing the cost of practice sessions.
Both cartridges are excellent for self-defense or use in service style handguns in urban or suburban settings. In addition, the versatile .357 is a viable choice for handgun hunting and general field use, applications for which the .40 S&W is not well suited. The .357 Magnum is also popular for use in lever action rifles, where it serves nicely as a short range (100 yard) hunting and plinking cartridge. By any rational standard, the .357 Magnum is the superior cartridge.
Copyright 2013 by Chuck Hawks. All rights reserved.