March 29, 2022
The .357 SIG is a bottlenecked, high-velocity handgun cartridge designed by a collaboration between SIG Sauer and Federal Ammunition Company in 1994. This came about, much in the same fashion as the .40 Smith and Wesson, as a response to the "poor performance" of 9mm Luger LE loads of the time. Much of this "need" for more effective new handgun cartridges stemmed from the 1986 FBI shootout in Miami, involving two bank robbers and multiple (outgunned) FBI agents. The firearms used were Smith and Wesson Model 13 .357 Magnum revolvers (loaded with .38 Special ammunition) and primarily Smith and Wesson 9mm semi-automatic handguns loaded with Winchester’s 9mm Silvertip 115-grain JHP load.
During this now infamous shoot-out, the assailants survived multiple center mass hits from the Winchester 9mm JHP load, with minimal effect, as not enough disruption of vital organs was achieved. Post autopsy, it was found that one of the 9mm Silvertips had a trajectory straight for the heart of one of the gun men, but stopped a mere inch short. This shootout not only ignited serious modern scientific studies of terminal wound ballistics by the FBI, but also led to looking outside the 9mm and other traditional cartridges for LE service pistols. Fast forward to the early 1990s, post FBI transition from the 10mm Auto, and both the .40 S&W along with its .357 SIG brethren were born.
The .357 SIG was intended to mirror the ballistics of the vaunted .357 Magnum when fired from a 4-inch barrel. Why the .357 Magnum? Simply due to the fact the 1935 vintage .357 Magnum has an excellent reputation as a real world man-stopper, especially when loaded with 125-grain JHPs. Initially designed on SIG Sauer's P229 offering, this 12-round offshoot of the P228 9mm offered the user good capacity, reliability, accuracy and a recoil absorbing alloy frame. The pair matched well, and was initially adopted by multiple government agencies including the U.S. Secret Service and Air Marshals, with several police agencies quickly following suit.
Unfortunately, the .357 SIG has fallen well-short of its initial design claims, with many loads giving velocity performance barely above that of modern 9mm +P offerings. While the .357 SIG is more than capable of better performance than its 1,350 feet per second advertised velocities, it seems that most commercial companies load a rather mild cartridge. Not all companies do this, there are some notable exceptions, but many do.
Owning a SIG Sauer P229 in both 9mm and .357 SIG (as well as a P226 in both), I have a rather unique opportunity to test both cartridges on even playing fields, with no handicap or real "difference" between the two handguns. So, how does the .357 SIG stack-up against its intended target, the .357 Magnum, as well as the 9mm Luger from corresponding barrel lengths? The results are pretty shocking. Directly comparing the high velocity .357 SIG 125-grain Gold Dot from Speer against the 124-grain +P 9mm Gold Dot, results were interesting to say the least. From a 4-inch P229, the .357 SIG Gold Dot produced a velocity average of 1,296 feet per second at 10 feet. This is a 10-shot average from a ProChrono. From a P229 9mm and a Glock 19 with corresponding barrel lengths, I achieved a 10-shot average of 1,201 feet per. This is a deficit of only 95 feet per second, or 7.91% from the 9mm +P Gold Dot to the Speer Gold Dot .357 SIG.
The Federal Premium 125-grain JHP faired a bit worse in the test, with a 10-round average velocity of 1,265 feet per second from the P229. It was the mildest shooting .357 SIG load of the bunch, coming in at 6.29% under the 1,350 feet per second advertised velocity mark and only 5.32% over the Speer Gold Dot 124-grain 9mm +P. If it is marginally better than a 9mm, how does it compare to a .357 Magnum, especially the "king of the hill" 125-grain Remington Express and Federal Classic Semi-Jacketed Hollow Points?
The .357 Magnum and the hard hitting 125-grain SJHP from Remington and Federal are both packaged with an advertised velocity of 1,450 feet per second, which equates to a total of 585 foot-pounds of energy. While most ammunition offerings either fall slightly short or barely meet advertised velocities from a 4-inch handgun barrel, the .357 Magnum surpasses it and by a decent margin. The Federal Classic 125-grain chronographs at 1,550 feet per second, while the Remington clocks in at 1,536. This is a 10-shot average from a 4-inch barrel, Smith and Wesson Model 19 K-frame "Combat Magnum" revolver.
A direct comparison of the Federal 125-grain JHP .357 SIG to the Remington Express 125-grain SJHP .357 Magnum shows a 21.42% difference in velocity, with the advantage clearly going to the Magnum, at a 271 feet per second advantage. Muzzle energy (or rather, energy measured at 10 feet) shows a 10-shot average of a respectable 444 foot-pounds of energy for the SIG. The .357 Magnum on the other hand pulled an astounding average of 655 foot-pounds. That is a 47.52% increase in muzzle energy over the .357 SIG, to put it in a better perspective, that is adding the muzzle energy of a 90-grain Cor-Bon .380 Auto +P on top of the .357 SIG.
The Federal Classic 125-grain .357 Magnum was the fastest of the two, producing a 10-shot average velocity of 1,550 feet per second, equating to 667 foot-pounds of energy. Compare this to the 125-grain Gold Dot .357 SIG at a respectable 1,296 feet per second and 466 foot-pounds of energy. While the SIG proves to be a formidable cartridge, and quite capable, it simply falls short of its target goal (competing with the .357 Magnum). The SIG has a deficit in velocity of 254 feet per second, or 19.59% and muzzle energy difference of 254 foot-pounds, or 43.13%.
These are pretty substantial differences in performance between the two cartridges, but the .357 SIG does have several distinct and unique advantages over the Magnum. The typical capacity of a Smith and Wesson K or L frame is 6 to 7 rounds, while the P229 has a capacity which doubles this at 12. The .357 SIG, while having a slightly obnoxious blast and report in comparison to traditional semi-auto duty calibers is mild mannered in comparison to a full-house 125-grain .357 Magnum. Muzzle flash is noticeably different in the SIG over even a +P+ offering in 9mm, but is practically non-existing when comparing it to the flame-throwing Magnum. In short, the .357 SIG, while loud is substantially better mannered than its Magnum counterpart.
While it seems the .357 SIG has been overshadowed by modern 9mm ammunition offerings and bullet technology, it does offer several unique abilities that set it apart from the 1901-vintage 9mm Luger cartridge. These abilities could lend themselves well to outdoorsmen, hunters, and areas with high concentrations of bear, large cats such as mountain lion or other dangerous animals. While I personally would feel massively under-gunned in "griz country", most dangerous animals found in the lower 48 could be effectively stopped with the .357 SIG and proper projectiles.
The Hornady XTP 147-grain offering in the .357 SIG offers exceptional penetration of nearly 18-inches in 10% ballistic gel, produces chronographed velocities of 1,200 feet per second (1,199 10-shot average) at 469 foot pounds of energy from a SIG P229 and is very mild recoiling. It is very accurate, with low muzzle flash and blast in comparison to its 125-grain counterparts. This 147-grain offering brings a 251 feet per second increase from Hornady's 147-grain XTP 9mm and its 949 feet per second velocities. This is a 26.44% increase in velocity and an astonishing 60.03% increase in muzzle energy. To say the .357 SIG offers good performance with heavier bullets is a gross understatement.
Outside of its flat trajectory and better than expected performance with heavy projectiles, the .357 SIG offers mediocre performance from 4-inch barrels with projectile weights that most consider for duty use or self-defense. With performance barely exceeding the 9mm +P with medium weight projectiles, and falling well-short in the performance department when comparing it to the .357 Magnum, it seems the .357 SIG may have fallen to the wayside and no longer fits its intended design parameters.
While companies such as Underwood Ammo, Buffalo Bore and Double Tap do offer loads with impressive velocity numbers, the question becomes are their projectiles actually designed for these higher velocities? It must be distinctly understood that projectiles perform at their peak efficiency within their designed velocity parameters. Companies design and produce their bullets to perform within a threshold of velocities. If these velocities are compromised drastically on either end of the scale, projectile failure is an expected result.
We have studied the results of projectiles failing to meet the minimum velocity, but haven't touched on surpassing the maximum. Ultimately, a spike in impact velocity past what the projectile is designed for, will result in rapid, near instantaneous, expansion. The best way to describe this is "over-expansion" if you will. This often results in the projectile fragmenting and the end result is typically shallow penetration that often falls well-short of the FBI minimum of 12 inches in 10% ordnance gel. This is viewed as a projectile failure by most, including myself.
This ultimately means the .357 SIG is practically stuck in the 1,300 to 1,375 feet per second mark for most self-defense projectiles. Is it worth the added recoil, blast, muzzle flash and reduction in magazine capacity of 2 to 3 rounds compared to the 9mm? In my opinion, no, it is a cartridge that has seen its day. Even the Secret Service, as of 2019, has replaced it with the 9mm Luger. The .357 SIG had a fair run, but ultimately the sun has set on this cartridge.
If you have any thoughts or comments on this article, we’d love to hear them. Email us at FirearmsNews@Outdoorsg.com.
About the Author:
Michelle Hamilton has a Bachelor’s degree in Criminal Justice/Homeland Security, is a serious student of wound ballistics, military history, small arms design and manufacturing and is a competitive shooter.