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The .357 Sig Pistol Cartridge for IPSC Competition Shooting?

The Sig Sauer P229 chambered for .357 Sig is currently used by both the US Secret Service and US Federal Air Marshall Service. Its use by these two organisations has increased both the Sig pistol’s and the .357 Sig’s appeal to the law enforcement market., Posted in Accesories

The .357 Sig Pistol Cartridge for IPSC Competition Shooting?
The .357 Sig Pistol Cartridge

THE .357 SIG pistol cartridge was produced in a joint venture between German firearms manufacturer Sig Sauer and the American ammunition manufacturer Federal Cartridge Company. While it is based on a .40 S&W cartridge case necked down to accept a 9mm  ( 0.355 inch ) bullet, the .357 Sig cartridge case is slightly longer than the .40 S&W.

.357 Sig

The .357 Sig was developed for law enforcement use to try and duplicate the performance of the .357 Magnum revolver round and now also sees increasing use in IPSC competition shooting as well. Like many other calibres, it is slightly misnamed, as the .357 Sig actually uses .355 inch ( 9mm ) diameter bullets.


The .357 Magnum revolver round when loaded with 125 grain JHP bullets was the favourate load carried by law enforcement in their revolvers. Reviews of both police and self defence shootings showed this caliber to have a 90 % plus effectiveness rating.

Developed in 1994, the new cartridge was named "357" to highlight its purpose, which was to duplicate the performance of 125 grain .357 Magnum round fired from a four inch barreled revolver, in a cartridge designed to be used in a semi automatic pistol. Until the .357 Sig, there was no practical semi automatic pistol round with comparable performance to the 125 grain .357 Magnum revolver round. In examining law enforcement and civilian self defense shootings in the USA it showed that in the .357 Magnum calibre a 125 grain jacketed hollow point ( JHP ) bullet fired from a four or six  inch barreled revolver at 1350 to 1450 feet per second ( fps ) was over 90 % successful at stopping an assalent with one solid torso shot. The switch from revolvers to semi automatic pistols for law enforcement use in the USA started in the late 1980’s and accelerated in the early 1990’s. Before the transistion was complete the most common round that officers carried in their three fifty sevens was the 125 grain JHP.


The .357 Sig cartridge was developed to duplicate the performance of the .357 Magnum 125 grain JHP revolver round in a cartridge designed to be used in a semi automatic pistol.

.357 Sig Devlopment

The .357 Sig provided a self defense cartridge to duplicate the performance of a 125 grain .357 Magnum, but from a semi automatic pistol. The .357 Sig was the first modern bottleneck commercial handgun cartridge since the early 1960s, when Remington introduced the .22 Remington Jet (1961), which necked a .357 Magnum case down to take a .22 caliber bullet, and the .221 Remington Fireball (1963). Soon after the .357 Sig, other bottleneck commercial handgun cartridges appeared. The .400 Corbon (1996) necked the .45 ACP down to .40 calibre; the .25 NAA (1999), necked the .32 ACP down to .25 calibre; and the .32 NAA (2002), necked the .380 ACP down to .32 ACP calibre.

Most .40 S&W pistols can be converted to .357 Sig by replacing the barrel and sometimes the recoil spring must be changed as well. Pistols with strong recoil springs can accept either cartridge with just a barrel change. Magazines usuallly will function between the two cartridges in some pistols, while in other cases the magazine have to be formed to suit the specific dimensions of a specific calibre. The .357 Sig is loaded to higher pressures than the .40 S&W and may not be suitable for use in all .40 S&W chambered pistols and there may be accelerated wear in certain models and makes.#

The goal of the .357 Sig project was to attain of performance of .357 Magnum loads and +P and +P+  9mm loads ( 9x19mm Parabellum ). The +P and +P+ relate to Plus Pressure and Plus Pressure Plus rounds that are loaded to velocities above the standard factory loadings. The .357 Sig accomplishes this goal with a 125 grain bullet. The recoil of the .357 Sig cartridge is strong, often noticeably more so than the .40 S&W, but not so much as full power 10 mm Auto loads, or the original .357 Magnum when fired from a revolver.


From left to right the 9mm, .357 Sig, .40 S&W and the .45 ACP are the four most commonly used calibres used in law enforcement work.

Because the .357 Sig fires at relatively high pressures, muzzle flash and noise are significant with standard loads, even with longer barrels. Utilising loads with specialised powders can reduce the muzzle flash.


Although the .357 Sig design is based on the .40 S&W case, reloaders cannot form .40 S&W cases into .357 Sig brass. While the two cases are identical in rim diameter, using the .40 S&W case will result in a case that is approximately 0.020 inch (0.50 mm) too short. Cartridges that are too short can result in malfunctions. The upper pressure limit is lower for the .40 S&W cartridge at 35,000 pounds per square inch ( PSI ) than the 40,000 PSI for the .357 Sig.


When US Law Enforcement switched from revolvers to semi automatic pistols the most commonly calibre carried was the 9mm. A smaller number of forces carried the .45 ACP. The .40 S&W is now the most commonly carried calibre by US police forces, but the .357 Sig is now seeing increasing use.

Choosing the correct bullet type is extremely important when handloading the .357 Sig cartridge. The short neck of the casing makes the use of standard roundnosed bullets impractical. There is simply not enough flat area for the neck of the cartridge case to grip the bullet, so flat point bullets that have a longer parallel bearing surface are used. Various 9 mm hollow point bullets can also be successfully used.

With a relatively high velocity for a semi automatic round, the .357 Sig can duplicate reach the performance of the .357 Magnum loaded with 125 grain bullets. The typical commercial loadings using 125 grain bullets, fired from a four inch revolver barrel, propels a 125 grain bullet at 1350 fps. The typical .357 Sig load propels the same bullet to 1,350 fps from a four inch pistol barrel.


In the past year the .357 Sig has seen a large increase in use in IPSC competition, especially in Australia and Denmark.

Documented police shootings have confirmed the .357 Sig’s ability to not over penetrate the body. Ballistic gelatin testing shows 16 inches of penetration into gelatin after passing through heavy clothing using a 125 grain Speer Gold Dot JHP. The Virginia State Police have had several documented officer related shootings involving the .357 Sig. In every case the felons stopped instantly with one shot, except one individual who was shot several times while attempting to murder an officer. The bullets did not exit the felons, or were stopped in their clothing upon exiting. This proved that even at such high velocities, the .357 Sig when used with adequate expanding hollowpoints will not over penetrate soft tissue. The same police department has also reported that attacking dogs have been stopped dead in their tracks by a single shot, whereas the previous load carried by the Virginia State Police was the subsonic 147 grain 9 mm duty round would require multiple shots to incapacitate an attacking dog.


The .357 Sig was designed to duplicated the performance of the .357 Magnum revolver round, when fired from a semi automatic pistol.

The bottleneck shape of the .357 Sig cartridge assists in reducing feeding problems. This is because the bullet is initally channeled through the larger opening for the cartridge case before being seated in the barrel throat as the slide goes fully into battery. Flat point bullets are seldom used with other semi automatic pistols because of feeding problems. However, such bullets are commonly seen in the .357 SIG cartridge and are quite reliable, as are hollow point bullets.


When loaded with Hornady XTP 147 grain JHP bullets, Ralf’s STI pistol in .357 Sig calibre will produce 10 shot groups around one inch in size when fired from a bench rested position. The group shown here is 23 milimetres in size, which is just under one inch.

The .357 Sig fires a .355 inch calibre bullet at higher velocities than most bullets of that caliber are designed for. Very few bullets have been designed specifically for the .357 Sig, and .357 Magnum bullets that are designed for the same velocity range cannot be used due to their 0.002" larger diameter. Because of this, there are fewer ammunition choices in .357 Sig than one might expect for a cartridge using .355" diameter bullets.

Sig Sauer Pistol

The Sig Sauer P229 pistol in .357 Sig is currently the standard issue firearm carried by agents of the United States Secret Service, the Texas Sheriff's Office, the North Carolina State Highway Patrol, Delaware State Police, Alameda County Sheriff's Office, Virginia State Police, Federal Air Marshals and the Treasury Inspector General for Tax Administration. In most cases, it has replaced .45 ACP, 10 mm, .40 S&W and 9 mm chambered pistols. In 1995, the Texas Department of Public Safety became the first government agency to issue the .357 Sig. The Tennessee Highway Patrol presently issues the Glock 31 pistol chambered in .357 Sig. The Canadian Forces Special Operations unit Joint Task Force 2 uses Sig P226's chambered in .357 Sig, as well as Canadian Naval Boarding Parties who use Sig P225's in .357 Sig. The Bedford Heights Police Department, Ohio currently issues the Glock models 31 and 32 in .357 Sig.


The .357 Sig develops similar power to the .357 Magnum revolver, but has an advantage by the fact that a pistol in .357 Sig carries between two and three times more ammunition than a six shot revolver.

Introduced to be an autopistol round that almost matches the wound ballistics of the top ranked manstopping 125 grain .357 Magnum revolver load, the .357 Sig is now seeing increasing law enforcement use. Enough feedback from street shootings now exists to determine that the .357 Sig has lived up to expectations.

A significant number of police departments have bought .357 Sig calibre pistols due to the fact that the U.S. Secret Service, which protects the President of the United States and the post 9-11 formed Air Marshall Service, which is tasked to prevent the future hijacking of aircraft, use this calibre. The state troopers of Delaware, Virginia, Texas, New Mexico and North Carolina have all adopted the .357 Sig. New Mexico chose the Glock 31 pistol to chamber it, and North Carolina, the Beretta Cougar. Many other units use the Sig Sauer pistol. Texas chose the P226, while Virginia and Delaware adopted the more compact P229.


Chambered in .357 Sig, Ralf’s STI Executive pistol will see a lot of use in the European IPSC match circuit.

Numerous municipal and county law enforcement agencies have also gone to the .357 Sig round. With all these law enforcement officers carrying this fairly new caliber, enough street shootings have taken place to bring a performance assessment of the .357 Sig out of the realm of theory and into real world reality.


With the .357 Sig Ralf recommends using the heavier 9mm bullets to keep the recoil manageable. Here this Hornady XTP 147 grain JHP bullet is loaded to an overall length of 31.00 milimetres.

The .357 Sig was developed in 1994 by Federal Cartridge Company and Sig Arms. Factory loaded ammunition is available from Federal, CCI – Speer, Sellier and Bellot and Winchester USA, and others. The most common load is the 125 grain bullet ( JHP or FMJ ) at 1350 fps, which delivers 510 ft. lbs. of muzzle energy from a four inch pistol barrel. So for law enforcement use, the .357 Sig will be a very good performer on the street with JHP bullets.


The .357 Sig Pistol Cartridge – an alternative for IPSC Standard Division?

If you are competing in IPSC Standard Division with a .40 S&W calibre pistol, why would you want to switch from the forty to the .357 Sig? Most likely you won’t! However, if you live in a country such as Australia or Denmark where pistol calibers exceeding 9mm diameter are not permitted and you would like to be able to shoot a major calibre pistol in Standard Division, well then .357 Sig is the way to go.


Seen here shooting a STI pistol in .40 S&W calibre, Ralf Jensen used a STI .357 Sig calibre pistol in the 2009 European IPSC match circuit.

In this part of the article one of the world’s top IPSC Standard Division competitors and STI European team member Ralf K. Jensen will be sharing his views with Practical Handgun on pros and cons of shooting a pistol chambered for .357 Sig, as well as information on his new hot STI Executive .357 Sig pistol setup which he has used when shooting Standard Division on the European IPSC match circuit in 2009.


This STI barrel is chambered in .357 Sig and provides superb accuracy with a variety of factory and reloaded ammunition.

As a resident of Denmark and competing in IPSC Standard Division Ralf has the problem of how to shoot major calibre in international competitions, which is the same problem that the Australian’s have. The solution so far has been using borrowed equipment in .40S&W from fellow STI European Team members. But using borrowed equipment just is not optimal, as there is no substitute for your own pistol. Pre 2007 to make major scoring factor in Standard Division the minimum calibre was .40" / 10mm. Now with the new rules in IPSC ( that came into effect end of 2007 ), you can shoot major scoring factor with a .357 Sig, provided of course the minimum IPSC power factor of 170 is achieved.


Federal factory ammunition produced groups of two inches from a rested position from the STI pistol chambered in .357 Sig.


Getting a magazine that holds 18 or 19 rounds to work with 100% reliability took a bit of work. Utilising modified magazine tubes, springs and followers and base plates from different suppliers eventually lead to a working solution.


Ralf teamed up with Danish gunsmith Kristian Pedersen ( ) to create a competitive STI pistol setup in .357 Sig calibre. Ralf uses a STI Executive pistol ( ) in competition and they provided him with barrels and recoil springs with which to carry out the experimental work.


In the first half of 2008 Danish gunsmith Kristian Pedersen and Ralf experimented with getting the .357 Sig to work in his two STI pistols.


Here Kristian takes a dimensional measurement of the magazine body. He converted a STI magazine in .38 Super calibre to work with the .357 Sig calibre.

Ralf commented “I though that this would be an easy task, but it was not easy at all, and we used the first half of 2008 experimenting to develop the best possible competition setup in .357 Sig.”,  Ralf started the project with the same magazine setup used by his STI teammate Gregory Migdley. “I used a Rescomp ( South Africa ) high capacity magazine body in .40 S&W, a Grams Engineering ( USA ) FKS-11 spring and follower kit and Schuwiduu ( Austria ) base pads. That setup gave me 18 rounds and even 19 rounds in .40 S&W if you trim 1½ coils off the magazine spring. It seemed logical to use the same parts for .357 Sig. However, this setup produced severe nose dives, with the bullet jamming against the feed ramp while trying to chamber in the barrel. No matter how much experimentation was done with the feed ramp, overall bullet length and bullet shapes, they never achieved better than 300 to 400 rounds without a serious jam.”


Here Ralf is pictured with his STI Executive in .40 S&W calibre at the 2007 European IPSC Championships in France. Now he will be making more use his STI Executive in .357 Sig calibre.

“The bottlenecked shape of the case should make feeding problems almost non existing.” commented Ralf. “In theory that's true, but in reality it’s not true for 2011 type pistols and magazines. If you use Rescomp / SVI / SPS magazines for the .357 Sig I’ve experienced profound tendency for the bullets to nosedive. .40 S&W STI magazines can be used, provided they are not modified. But that gave me too little capacity.”


In some countries that maximum calibre allowed for civilians is 9mm / .38 calibre. This has seen an increase in the use of the .357 Sig by IPSC competitors in these countries.

The Challenge

The challenge was to come up with a magazine set up, that provided outstanding magazine capacity ( 18 or 19 rounds ) without sacrificing one bit of reliability. They achieved their goal. The solution proved to be a heavily modified STI magazine tube in .38 Super calibre in combination with the Grams FKS-11 kit and a Schuwiduu base pad. “We spend MANY hours coming up with a design that gave high capacity (18-19 rounds ) without sacrificing reliability.”, emphasized Ralf.


Here Ralf is action at the Danish Rooster Mountain Match. Denmark is one of several countries that have restrictions on calibre ownership and have therefore seen an increase in use of pistols chambered for the .357 Sig.

The gunsmith even had to build a new tool that modifies the STI magazine tube in several ways. It was worth the experimentation as they now have achieved 100 % reliability in combination with a 18 round capacity magazine. One magazine will reliably take 19 rounds, but it takes a real effort to load the last round. “The pistol is 100 percent reliable and I wondered how many rounds I could fire without a malfunction” comments Ralf. “After firing 12000 rounds of .357 Sig ammunition without a single malfunction I stopped counting”.

What’s good about shooting .357 Sig?

Well, first of all Ralf brings up accuracy. “I have always found the STI .40 S&W pistol to very accurate, but the accuracy of my two .357 Sigs is even better”, he comments. It is simple the most accurate pistol Ralf has owned so far. The best groups were achieved with Hornady 147 grain XTP bullets ( ) over a heavy dose of Vectan Powder ( ), which achieved a ten round group of less than one inch at 25 yards. Federal 125 grain factory ammunition ( which were very hard recoiling ) produced a group of 1 ½ inches. With Sellier and Bellot 140 grain factory ammunition the pistol produces 10 shot groups of 2 inches at 25 yards. The Federal 125 grain factory round will produce 1420 fps out of Ralf’s STI, for a power factor of 177.5.


Developed by the German firearms manufacturer Sig Sauer and the American ammunition manufacturer Federal Cartridge Company, the .357 Sig now sees wide spread use in law enforcement and competitive pistol shooting.

“The accuracy is just so outstanding in the STI pistol chambered for .357 Sig. This is just a theory of mine, but I think the rifling twist in the barrel is very well suited to the high velocities achieved when using 125 grain and 147 grain bullets to make major power factor of 170”.

“But I still prefer to shoot 180 grain bullets in competition because of the lower recoil, however 180 grain .355 bullets are hard to come by, but they exist. I’ve experimented with shooting .357 diameter bullets in my .357 Sig, which in reality is a .355 barrel. They can be used, but care should be taken using slower powders and longer over all length to make sure case volume is large enough to reduce initial pressures. People have been shooting .357 diameter bullets in their .38 Supers for ages, but that doesn’t necessarily make it right. With the .357 Sig bullet a 180 grain bullet in .357 diameter is very long and will give you higher chamber pressure, so you really need a very slow burning powder in the same ballpark as what the Open Division shooters use”.

Ralf or the author of this article assumes no liabilities for loading experiments carried out after reading this article. There is a large amount of loading data available for the .357 Sig on the internet, so spending a little time on the Internet could be worthwhile.

Due to the volume of ammunition that IPSC competitors use and to tailor the ammunition to suit your pistol, this means that you reload your own ammunition, as Ralf does. “The .357 Sig could probably turn out a bit cheaper to reload than the .40S&W, because you can use a 9mm bullet instead of a 10mm / .40 bullet and the costs of cartridge cases are the same as .40 S&W, especially if you use once fired brass from the USA. A lot of police departments have switched to .357 Sig, which means that there is an available supply of once fired cartridge cases to reload”.

Downsides to Shooting .357 Sig?

Recoil. Perception of recoil is always a subjective feeling, but Ralf is convinced that there is significantly more kick, especially when using a 125 grain bullets to make major, when compared to a .40 S&W using a 180 grain bullet. “The lighter 125 grain bullets give a very hard, snappy recoil, meaning that the best solution with the .357 Sig is to use either a 147 grain bullet, or even better a 180 grain bullet, in which case recoil is much more softer and managable, and comes much closer to the feeling of a 180 grain .40 S&W load”, he comments. “But it’s still not as soft shooting as the .40S&W, which I think is the result the higher pressure in combination with the slower burning powders in .357 Sig”


When US law enforcement switched from the revolver to the semi automatic pistol the most popular calibre carried was the 9mm ( left ). With a performance that duplicates the .357 Magnum revolver round, the .357 Sig ( right ) is now seeing increased use.

Conversion from .40 S&W to .357 Sig

To convert a .40 S&W you need is a new barrel and maybe a heavier recoil spring. If you leave the STI .40 S&W magazines unmodified they should work OK with a .357 Sig, provided overall length of the loaded cartridge is long, a minimum of 30.0 mm, but of course you will not get 19 rounds in them and achieve 100 percent reliability. You will need a magazine capacity of 18 to 19 rounds to be competitive in IPSC Standard Division.


Currently the .40 S&W ( left ) is the most commonly used calibre in US law enforcement. The .357 Sig ( right ) was developed from the .40 S&W, were the cartridge case is necked down to accept a 9mm calibre bullet.

The Verdict

Since starting this project Ralf has moved and now lives in Sweden, which is next door to Denmark. In Sweden the civilian ownership of .40 calibre pistols is legal. I asked him will he use his .40 STI or .357 Sig STI? “Actually I can't really decide if I should shoot .40 or .357 Sig. I'm leaning towards the 357 Sig, because of the extreme accuracy, which I love. On the other hand, shooting the .40 S&W round gives you a slightly softer recoil and lower pressure and a 19+1 magazine capacity with greater ease. That’s a competition advantage you can’t ignore. Also the reloading of .40 calibre ammunition is a bit easier.” Ralf’s final comment was “I've recently purchased a Dillon 1050 in 357 Sig, so I guess my 357 Sig STI will still get some use. But the truth is that for the 2010 IPSC season I plan on switching back to .40S&W.”

Active IPSC competitors who live in a country where legislation does not permit you competing with a .40 S&W, or who have a craving for extreme accuracy will take a hard look at the .357 Sig. 

For Further Information

Danish gunsmith Kristian Pedersen can be contacted at

Ralf Jensen ( ) can be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it.


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