Although nearly identical in dimensions other than length, the .38 Special and .357 Magnum cartridges are different in many regards. Yet, their similarities are one of the signs of a shared heritage and history.
Learn everything you’ve ever wanted to know about these two classic revolver cartridges, their similarities, their differences, and what makes their corresponding firearms unique.
Brief History of the 38 Special
The .38 Smith & Wesson Special cartridge is a rimmed, straight-walled, centerfire revolver cartridge, first introduced by Smith & Wesson in 1898 and initially designed for the original Smith & Wesson Military & Police revolver.
Since then, the cartridge has received numerous designations: .38 S&W Special, .38 Special, .38 Spc, .38 Spl, or simply .38. More rarely, it is also called 9x29mmR or 9.1x29mmR.
Behind the name
Although the name of this caliber implies a .38” diameter bullet, in reality it employs a 0.357” projectile. The “.38” designation comes from the approximate diameter of the casing of the projectile itself.
.38 Special is an improvement over the older US military-issued handgun cartridge, the .38 Long Colt (.38 LC). By the late 19th century, .38 LC had demonstrated its inadequacy and low stopping power in the Philippine-American War, causing the US Army to switch back to the older, more powerful .45-caliber Colt Single Action Army.
Originally, .38 Special was a blackpowder cartridge, much like .38 LC and .45 Colt. However, ammunition manufacturers quickly switched to modern smokeless powders after the turn of the century. The original cartridge accepted 158-grain bullets sitting above 21 grains of blackpowder, developing 17,500 psi of maximum pressure and 850 to 900 ft/s of muzzle velocity.
Modern standard-velocity .38 Special ammunition typically features 125-grain bullets, developing a similar average muzzle velocity of 900 ft/s from a typical 4” barrel.
.38 Special is dimensionally identical to .38 Long Colt (and its predecessor, the .38 Short Colt) in every way except length; the .38 Special case is longer to accommodate the extra powder. In turn, this allows a .38 Special revolver to shoot .38 LC and .38 SC safely.
The velocity race
Although initial sales were slow, the revolver and its cartridge quickly gained acceptance, particularly after the US Army and Navy placed an order for a few thousand M&Ps. Quickly afterward, the .38 Special cartridge and its 158-grain lead round nose (LRN) soon gained a following among civilians and law enforcement officers.
As a cartridge initially designed with blackpowder in mind, standard .38 Special ammunition develops a relatively low pressure. When the switch to smokeless powder occurred, manufacturers realized they needed much less propellant to achieve the same velocities as the blackpowder version, leaving a significant amount of empty space inside the case.
This fact led to the development of high-velocity versions of the .38 Special cartridge, loaded with a higher quantity of powder to develop greater muzzle velocity and energy.
Although hand-loaders have long experimented with the cartridge to achieve similar results, certain ammunition manufacturers officially produced high-velocity versions of the .38 Special, typically to meet law enforcement or military needs.
.38 Special Hi-Speed (.38/44): First introduced by Smith & Wesson in 1931, the .38 Special Hi-Speed, designed to be fired out of the larger, more robust N-frame Model .38/44 revolver, was available in three bullet weights: 110 grains, 150 grains, and 158 grains. The 158-grain version was capable of reaching up to 1125 ft/s at the muzzle.
.38 Special +P: Throughout the 1950s and 1960s, police departments and federal law enforcement agencies continued issuing .38 Special firearms to their officers. However, following incidents where officers needed multiple shots to stop an assailant, ammunition manufacturers began offering a high-powered version of the cartridge, known as .38 Special +P. The +P designation refers to the high pressure (20,000 psi, roughly 14% more than standard .38 Special), resulting in an average muzzle velocity of 1000 ft/s from a typical 4” barrel.
FBI Load: In 1972, the Federal Bureau of Investigation adopted a variant of the .38 Special +P load tipped with a 158-grain, unjacketed lead semi-wadcutter hollow point (LSWCHP) bullet. This load proved highly effective, resulting in a much higher rate of one-shot stops.
.38 Special +P+ / Treasury Load: Jointly developed by Federal and Winchester, the Treasury Load was designed to meet the needs of the Department of Treasury. This cartridge further pushes the envelope, producing even more pressure than the +P cartridge (22,500 psi, approximately 28.5% higher than standard). The Treasury Load features a 110-grain jacketed hollow point to achieve maximum velocity, capable of 1200 ft/s out of a 4” barrel and 1100 ft/s out of a 2” snub-nose. The high pressures require a modern revolver, preferably steel-framed, to avoid catastrophic failures.
How the .357 Magnum Came into Existence
Elmer Keith was among the first firearms experts to recognize the untapped potential of the .38 Special cartridge.
In the early to mid-1930s, Keith extensively experimented with high-velocity loadings, using the heavy-frame .38 revolvers such as the .38/44 Heavy Duty and Outdoorsman as the test platforms. These revolvers were built on the Smith & Wesson N-Frame, originally designed with the much larger .44 Special cartridge in mind.
Along with fellow experts Philip B. Sharpe and Douglas B. Wesson, Keith developed the original .38 Special Hi-Speed (.38/44) load. It featured the Keith-style bullet, an unjacketed semi-wadcutter (SWC) projectile with a wide meplat (65%, later 70% of the bullet’s overall diameter), and convex sides. This specific design concentrated most of the bullet’s volume outside of the case, leaving more room inside for extra powder.
Although the original .38 Special Hi-Speed (.38/44) cartridge was the industry’s first official attempt at producing factory high-velocity versions of the .38 Special, this cartridge was unsafe to shoot in standard .38 revolvers, presenting a significant safety issue.
Smith & Wesson addressed the problem in 1934 by introducing a new cartridge: the .357 Magnum.
When comparing the .38 Special vs. .357 Magnum cartridges, you’ll find they are identical in all but length, with the Magnum cartridge possessing ⅛” of extra length. These dimensions rendered the new round incompatible with regular .38 Special revolvers, requiring dedicated .357 Magnum platforms to shoot it.
The Magnum era
The birth of the .357 Magnum marked the beginning of the Magnum era of revolver cartridges.
The operating pressure of a typical .357 Magnum cartridge is 35,000 psi, exactly double that of .38 Special. Just as .38 Special revolvers could safely shoot .38 Long Colt and .38 Short Colt, .357 Magnum can safely shoot all .38 Special ammunition, including all high-velocity versions.
The first .357 Magnum revolver offered on the market was the Smith & Wesson Registered Magnum, appearing on the market in 1935, one year after the cartridge’s introduction. Registered Magnums were custom-ordered revolvers made and tuned to the customer’s specifications.
A typical .357 Magnum load features a 125-grain jacketed soft point (JSP) bullet with a powder charge capable of producing 1450-1500 ft/s of muzzle velocity from a 4” barrel and 1700-1750 ft/s out of a 6” barrel.
The .357 Magnum quickly gained notoriety for its substantial stopping power and high terminal effectiveness, translating into proven street effectiveness. As a result, many law enforcement agencies (most of which already equipped with .38 Special revolvers) switched to .357 Magnum with almost no other changes in logistics, using the Magnum loads for duty while keeping their existing stocks of .38 Special ammunition for training and practice.
In the civilian world, the .357 Magnum became a favorite for self-defense and target shooting applications. With the appropriate projectiles and loadings, .357 Magnum also became an excellent hunting cartridge in both handgun and rifle platforms.
Most of the firearms produced for this cartridge were revolvers and lever-action rifles. However, a small number of .357 Magnum semi-automatic pistols were also developed, such as the world-famous Desert Eagle and the 1911-inspired Coonan pistol.
As the first of the Magnum era cartridges, the .357 Magnum spurred decades of innovation in firearms and ammunition technology, resulting in the subsequent creation of ever-more-powerful magnum cartridges, pushing the boundaries of what a handgun caliber can do.
Some of the most notable examples include .44 Magnum, .41 Magnum, .454 Casull, .327 Federal Magnum, .475 Wildey Magnum, and .500 Magnum.
Today, long after leaving their mark on firearms history, both .38 Special and the .357 Magnum continue enjoying popularity. Modern factory ammunition in both calibers is widely available, and you can readily find a plethora of new and used firearms.
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