Compared: The .357 SIG and .38 Super Auto +P

By Chuck Hawks


This is a comparison of two mis-named pistol cartridges. Both are high velocity autoloading pistol cartridges that actually shoot .355" (standard 9mm) diameter bullets. Neither can equal the ballistics of the .357 Magnum revolver cartridge, although both have been promoted as such.

The case design of both cartridges is somewhat unusual for autoloading pistol cartridges. The .38 Super uses a semi-rimmed case, although modern .38 Super pistols headspace the cartridge on the case mouth, rather than the rim. (Early Colt Super 38 pistols did headspace on the small rim, which caused accuracy problems.) The .357 SIG uses a bottle neck case, rather than the straight wall case form typical of pistol cartridges.

The .38 Super was the high velocity queen of commercial auto pistol cartridges from its introduction in 1929 until the advent of the modern 10mm Auto and .357 SIG. The 10mm (a .40 caliber cartridge) is beyond the purview of this article, but the .357 SIG is the newest high velocity 9mm cartridge, so it is reasonable to see how it compares to the earlier .38 Super.

.38 Super Auto +P

The .38 Super is a souped-up version of the earlier .38 ACP, which was introduced in the Colt 1900 and 1902 autoloading pistols. The .38 ACP claimed a MV of 1040 fps with a 130 grain bullet.

In 1929, Colt got around to chambering their 1911 pistol, a much stronger design than the old 1902 pistol, for an improved version of the .38 ACP cartridge. The resulting .38 Super Auto cartridge for the 1911 pistol used the same case and bullets as the earlier cartridge, but loaded to much higher pressure for increased velocity. Winchester and Remington .38 Super factory loads launched a 130 grain bullet at a MV of 1280 fps.

Incidentally, there has never been a low pressure specification for the .38 Super. The superfluous +P designation was added in 1974 when such designations became popular for other cartridges, apparently to further distinguish the .38 Super from its look-alike (and by then obsolete) .38 ACP ancestor. Interestingly, the modern +P ammo is loaded to lower velocity than the traditional .38 Super load.

Today, .38 Super factory loads are available from both Remington and Winchester. Both companies load a 130 grain FMJ bullet at a MV of 1215 fps and Winchester offers a Silvertip JHP bullet at 1240 fps, which is more like it. This is the load we will use for comparison in this article. The SAAMI specified maximum average pressure (MAP) for the .38 Super +P is 36,500 psi.

.357 SIG

Introduced in 1994 by SIG and Federal and based on a necked-down .40 S&W case, the .357 SIG is the latest attempt at a high velocity 9mm cartridge. The inaccurate ".357" designation was chosen to invoke the mystique of the .357 Magnum revolver cartridge in the minds of gullible consumers.

Actually, the .357 SIG falls 100 fps short of .357 Magnum performance with a 125 grain bullet fired from a 4" barrel. Nevertheless, the .357 SIG is one of the most powerful cartridges designed for use in autoloading pistols. The SAAMI specified MAP for the .357 SIG is a whopping 40,000 psi, which I believe is the highest MAP of any autoloading pistol cartridge.

.357 SIG factory loads are offered by Federal, Hornady, Remington and Winchester, among others. The standard MV with a 125 grain bullet is 1350 fps. Winchester offers four .357 SIG loads using 125 grain bullets at 1350 fps. Among these is a JHP, which is the load we will use for comparison in this article.

The Comparison

We will compare Winchester factory loads using 125 grain JHP bullets in both cartridges. We will compare these loads in velocity, energy, trajectory and recoil. Since both cartridges use the same bullets, the bullet diameter, sectional density and cross-sectional area are identical. Note that the standard test barrel length for the .357 SIG is 4", while the Colt 1911 Super .38 pistol has a 5" barrel and this is the standard test barrel length for the .38 Super Auto cartridge.

Velocity

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 unknown ranges. Here are the Winchester published velocities in feet per second (fps) of our comparison loads at the muzzle (MV), 5 yards, 25 yards and 50 yards.

  • .357 SIG, 125 grain: 1350 fps MV, 1331 fps at 5 yards, 1262 fps at 25 yards, 1185 fps at 50 yards
  • .38 Super, 125 grain: 1240 fps MV, 1228 fps at 5 yards, 1181 fps at 25 yards, 1130 fps at 50 yards

The .357 SIG starts 110 fps faster than the .38 Super and maintains a 55 fps advantage at 50 yards. This bodes well for its energy and trajectory.

Energy

Kinetic energy is defined as the ability to do work; in this case, powering bullet penetration and expansion. Both are, of course, necessary for lethality. It is also worth noting that kinetic energy is a reasonably good indicator of potential effectiveness when comparing similar cartridges shooting similar bullets. Here are the Winchester energy figures in foot-pounds (ft. lbs.) for our comparison loads at the muzzle (ME), 5 yards, 25 yards and 50 yards.

  • .357 SIG, 125 grain: 506 ft. lbs. ME, 492 ft. lbs. at 5 yards, 442 ft. lbs. at 25 yards, 390 ft. lbs. at 50 yards
  • .38 Super, 125 grain: 427 ft. lbs. ME, 419 ft. lbs. at 5 yards, 387 ft. lbs. at 25 yards, 354 ft. lbs. at 50 yards

As expected, the .357 SIG shows a 79 ft. lb. energy advantage at the muzzle, decreasing to 55 ft. lbs. at 25 yards and 36 ft. lbs. at 50 yards. However, these are very good energy figures for pistol cartridges. While several revolver cartridges develop more energy at all ranges, among self-loading pistol cartridges only the 10mm Auto beats the .357 SIG.

Trajectory

Trajectory is not as important for a personal defense cartridge as it is for a hunting cartridge, as most defensive shooting scenarios take place at relatively short range at home or in the city. However, some folks carry their service autos for protection from two legged predators in the field, where much longer ranges may apply.

Without question, a flatter trajectory makes hitting easier as the range increases. Mid-range trajectory (MRT) shows the maximum bullet rise above the line of sight between the muzzle and the distance at which a gun is zeroed. Here are the mid-range trajectories for both cartridges at 50 and 100 yards.

  • .357 SIG, 125 grain: 0.7" at 50 yards, 3.2" at 100 yards
  • .38 Super, 125 grain: 0.8" at 50 yards, 3.4" at 100 yards

The .357 SIG shoots slightly flatter than the .38 Super, but the difference is inconsequential. Either cartridge is effective out to at least 100 yards.

Recoil

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. Here are some recoil energy (in ft. lbs.) and velocity (in fps) figures for our two cartridges, calculated for pistols weighing two pounds.

  • .357 SIG, 125 grain at 1350 fps: 6.6 ft. lbs. energy; 14.5 fps velocity
  • .38 Super, 125 grain at 1240 fps: 5.6 ft. lbs. energy; 13.4 fps velocity

The .357 SIG is somewhat more powerful than the .38 Super, so it kicks somewhat harder in pistols of the same weight. Since the Colt 1911 Super .38 pistol, the most common platform for the .38 Super Auto cartridge, is heavier than the SIG and Glock pistols most commonly encountered in .357 SIG, the .38 Super's lower recoil advantage will usually be greater than it appears here.

Conclusion

The .357 SIG clearly wins this comparison in the velocity and energy categories. In trajectory there is no practical difference between the two cartridges. The .38 Super kicks less in pistols of the same weight and considerably less in pistols of typical weight.

The .357 SIG and .38 Super are both good choices for self-defense in urban and suburban settings. Both cartridges offer good stopping power with appropriate bullets. They have more muzzle blast and sharper recoil than the ubiquitous 9mm Luger (9x19mm) autoloading pistol cartridge, but they can be controlled by most shooters.

Today, the selection of both guns and ammunition is significantly better in .357 SIG. This gives the .357 SIG a considerable advantage for contemporary shooters and is probably the critical deciding factor for someone considering a new, high velocity, 9mm pistol. However, anyone who owns a good .38 Super pistol is well armed and probably has no real need to upgrade to a new .357 SIG pistol.




Back to Handgun Cartridges

Copyright 2016 by Chuck Hawks. All rights reserved.


HOME / GUNS & SHOOTING / NAVAL, AVIATION & MILITARY / TRAVEL & FISHING / MOTORCYCLES & RIDING / ASTRONOMY & PHOTOGRAPHY / AUDIO