.357 SIG, Cartride, ammo, ammunition, bullet, SIG

.357 SIG

One of the sleepers of modern pistol cartridges is slowly slipping away from us.

By Wiley Clapp (RSS)
March 9, 2011

For reasons I do not understand, the great little .357 SIG cartridge is not getting the attention it deserves. It has been a viable self-defense and police-service load since 1994 and, while the on-the-shelf ammunition options were once pretty wide, they are slimming down by the year. New guns are likewise growing scarce, but there are some good signs, like the Smith & Wesson M&P357, in both standard and compact versions. At a point 10 years into the 21st century, the .357 SIG is nonetheless on a downhill slippery slope. This is a matter for serious consideration.

The .357 SIG cartridge was conceived at what was then SIG Arms in New Hampshire and developed jointly with Federal. It is just a little bit of an oversimplification to say that the round is a .40 S&W cartridge necked down to
9 mm, but that is the gist of it. This procedure does two basic things: First, it produces a 9 mm round that works well in pistols designed for the .40 S&W—the same case head means the extractor, ejector, firing pin, breech face and even magazine are the same for both—making the guns easy to manufacture. Second, the .357 SIG case may take 9 mm bullets at the front end, but its bottlenecked shape gives it the case capacity of much longer rounds—ergo, potentially higher velocity and energy levels. Remember, the .40 S&W was a round engineered for 9 mm-sized pistols, so the .357 SIG would make a much more powerful 9 mm-sized gun.


It got off to a roaring start in SIG’s excellent, mid-sized P229 pistol, and eventually made it to the full-sized P226 and single-column P239 compact. Glock also chambered small-, medium- and large-framed pistols for the round.

Smith & Wesson offered a few Sigmas and currently makes both large and small M&Ps chambered in .357 SIG. There were a few other guns, like early Beretta Px4 Storms, so there was no lack of choice in .357 SIG-chambered pistols. It was the ammunition and its performance that raised a host of questions.

I can’t recall another cartridge that drew the attention of ammo makers as quickly as the .357 SIG. Within a very short time span, we had ammunition from all of the big five American ammunition companies—Federal, Hornady, Remington, Speer and Winchester—as well as many smaller and foreign outfits. By a wide margin, the most-popular bullet weights were 124 and 125 grains. There were a small number of lighter loads and one or two heavier ones, but the 125-grain bullet was the virtual standard. Velocities with this stuff were pretty zippy, and it became obvious the cartridge was challenging the .357 Mag. in speed.

I once did an extensive shoot where I pitted the .357 SIG and the .357 Mag. against one another in guns with typical barrel lengths. The results got me called an outright liar by some and incompetent by others. To boil it down to basics, a range of 10 different 125-grain .357 SIG loads in a P229 pistol averaged 1,350 fps. A range of 10, 125-grain .357 Mag. loads in a Smith & Wesson Model 19 revolver with a 4-inch barrel averaged 1,270 fps. That is an 80-fps advantage to the SIG pistol. And by the way, the magnum lineup included that screaming-hot Remington load so popular with today’s wheelgunners.

People look at the stubby little bottlenecked pistol cartridge that comprises the .357 SIG and compare it to the long, powerful round with the magic word “Magnum” on the headstamp. We all know that connotation, and are just unwilling or unable to believe a semi-auto pistol cartridge could possibly measure up to it. But by keeping the yardsticks even, with bullets of the same weight for both guns, it does. Sure, the magnum revolver is much more versatile with ammo, using up to 180-grain bullets. It is better for a wider range of needs. But, that doesn’t change the fact that the SIG semi-automatic outran the mighty magnum on a level playing field.

In my first few years of affection for this curious little cartridge, I used some 6,000 rounds of the fodder. It is a snappy little round that takes a firm hand to control, but the cartridge shoots very flat out to 50 yards—maybe a little more. I can even stay on a B-27 target at 100 yards (OK, on most days). It should be obvious that modern semi-autos with deep magazines have a “the reload is in the gun” advantage. Smith & Wesson’s M&P357 has a 15+1 capacity. The company’s biggest .357 Mag. revolver is an eight-shot N-frame. That’s exactly half as many 125-grain bullets.

Shooters who look at that bottlenecked cartridge and predict trouble just haven’t tried it. I have yet to experience a malfunction in any .357 SIG pistol. That alone makes it superior fightin’ iron.

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29 Responses to .357 SIG

  1. Glad to hear I am not the only .357 Sig fan. I use a Glock 32 and consider it the ultimate carry gun. Compact, great capacity, and power to boot. Cost to reload is not materially different than 9mm or .40S&W either. Oh yeah, and it’s just plain FUN to shoot!

  2. Buck says:

    I can honestly say that until three days ago I have never shot this round. I was at the Glock Training center in Smyrna testing some new experimental ballistic plates. Having shot it a few times I’ll now have to go back and try it some more and see how I like it compared to my favorite 40 cal. It did seem a little snappier but proper grip fixes that.

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  4. Johnny C. Kitchens says:

    The 357 SIG sounds a lot like the 10mm Auto. One moment all the rage, then fade. The 10mm Auto keeps hanging in there with loyal fans and I hope the 357 SIG can as well, but it is slipping. I own both and they are both top performers…

  5. Cassino G/ says:

    I have to say the 357 SIG is the round that I, my Mother, my Brother, and most of my friends carry. One look at the potential of this load, (especially in a 4.5 inch barrel) and the selection of pistols, make it an obviously superior choice for a SD pistol! This is now the ONLY load I trust my life to! From Home Defense to Driver’s SD, this load shines! One of it’s main benefits is it’s inherit ability to easily penetrate intermediate barriers (Auto Glass, & Body Panels etc.) with enough energy remaining to incapacitate a BG! What more needs to be said?
    This round deserves serious consideration and respect!
    Also- if you have a 4.5 inch barrel, take a good look at the 147 grain loadings! Ultimate penetration without over penetration!

  6. TommyGun4169 says:

    I tend to disagree. It seems the 357 Sig is/has taken off over the mighty 10mm. There are many police agencies using the 357 Sig including but not limited to the US Secret Service, FBI, CIA, NJ State Police, Delaware, Texas, and others, beside the local police departments that use it. The only reason the 10 mm didn’t catch on is because of wimpy people pure and simple. They weren’t brought up shooting 357 and 44 Magnums like the old heads. I think the 357 Sig has a chance of a comeback and I noticed even online ammo stores have 2 to 3 pages of 357 Sig ammo compared to one page of 10 mm ammo. Once folks start realizing we have a gem here, it won’t go anywhere. It’s up to the public now, the law enforcement agencies already did their part.

    • rick says:

      I own both glock 29 & glock 32. Love the 10mm and the little sig is sweet too, i think both calibers wll be fine, the prob is people are just wusses nowadays. Simple az that.

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  8. Greg Lee says:

    I shoot 357 Sig in my Glock 22 with a Barsto Barrel & it shoots 1′ groups at 15 yes. It also reloads very well on my Dillon press. Used brass is easy & relatively cheap by the 1000 & I use 9mm flat nose bullets that work well & are much cheaper to buy then 357 Sig bullets. Round nose 9mm bullets will not seat properly in a 357 sig case. I read an article on LE national database of all police shootings that show the 357 Sig is one of the most effective one shot drop rounds available second only to the 45 acp. The
    Muzzle flash is also very impressive. A joy to shoot.

  9. Chad says:

    While it doesn’t have a huge share of the market, I don’t think the 357 Sig is slipping away. I think it will hang on and likely grow slowly in popularity. As a handloader, I think it is a great cartridge, especially considering the reloading costs are virtually the same as 9mm. I do have to strongly disagree about it ‘outrunning’ the 357 magnum though. Most factory 357 magnum ammo is watered down but is still generally a bit faster than the 357 Sig. However, when you compare ‘real’ 357 magnum loads, it has a definite advantage, even with lighter bullets. The two cartridges get compared a lot and understandably so but IMO, they are noticeably different animals. When loaded to it’s potential, the magnum is considerably more powerful and has the versatility to use heavy bullets offering deep penetration but at the expense of recoil and capacity. The Sig is limited to lighter bullets and gives up some performance but it is available in a more concealable package with less recoil and much greater capacity. Depending on the situation and the shooter each has advantages over the other. I own, reload for, and shoot both. The Sig does have advantages but the magnum is, without question, a more powerful cartridge. That said, depending on the particular load, there is some overlap between the two with factory ammo just as there is some overlap between the 357 Sig and the 9mm with some factory loadings.

  10. Scott says:

    Some Fish and Game Dept throughout the US have transitioned to this cartridge and have great success with it. Maine Warden Service, North Carolina Fish and Game, Pa Game Commission to name a few. Speaking with one warden from Maine, they have used it to dispatch road struck moose with great effectiveness, and an injured moose is one tough critter to deal with…

  11. Wes says:

    Mississippi Highway Patrol recently traded their G22′s for Gen 4 G31′s. I think the 357 Sig will be around a while. The G32 is my choice.

  12. Bill VanHorne says:

    I love this round in my sig 226. I also have the .40 barrel and prefer the .357 sig round. It is ‘snappy’ compared to the .40′s ‘push’. It feels like the gun runs faster. I just wish it was less expensive to purchase for practice.

  13. John says:

    The only thing holding this back is the cost of ammo on the civilian/retail side!!! Ammo companies are charging an unnecessary premium for it, and that is a major factor when people are looking for a new gun.

  14. Reyn says:

    I have a Glock model 31 in the .357 Sig. LOVE IT! It still amazes me that so many shooters have never even heard of this round.

  15. Lawman says:

    I use this caliber in my Springfield XDM with a Storm Lake conversion barrel. In reality I am carrying a 18 round .357 magnum.

  16. JJ357 says:

    I am so glad I stumbled across this article and all of your responses. I am a huge fan of the 357 Sig as my self given moniker well illustrates. I currently shoot a Smith and Wesson M&P 357 Sig, no mag safety, no internal locks and no external safety, just keeping my booger hook off the bang switch until it’s time to rock and roll. It sports APEX trigger and RAM, stippling and Surefire x300 and will be my primary WROL sidearm, the beauty here is that I bought a 40 barrel for it in case I run out of 357 Sig ammo in WROL I can always use the millions of 40 rounds purchased by…anyhoo! Great round, check out the Underwood Ammo, from my chrony it comes out at 1500+ fps generating some 630+ ft lbs of energy.

  17. JJ357 says:

    Forgot to mention that my magazines sport Arredondo extensions so I get 19 rounds of 357 magnum performance!

  18. Aaron says:

    Does the SIG 357 ammo come in anything other that JHP? Is there a more affordable round to shoot for practice?

    • JJ357 says:

      Yes, it comes in FMJ as well, MidwayUSA has Ultramax remanufactured ammo for $15.99 for a box of 50 rds, which is competitive with 40 S&W rounds; I buy it in bulk. You will find 40 S&W rounds cheaper from time to time, so get a 40 S&W barrel.

  19. Pat Slevin says:

    Chronograph this load. It is by far the most consistant load out there. 8.7 grs of Power Pistol and 124 gr Hornady XTP gives anywhere between 1400-1500 ft/sec. The low velocity is due to winter conditions and the high is in summer but the extreme spread is 19 ft/sec while the standard deviation is 7. Accuracy out to 50 yards is really, really good. This is the most consistant bullet I’ve ever run across the chronograph and those who’ve tried it know it is a great cartridge.

  20. Dano says:

    Mr Lee, apparently you aren’t aware of the latest FBI tests, as the 10mm & 357Sig were the only two calibers to crack their geletin block retainers. In a Texas shoot-out with a Semi Tractor, an officer emptied his 45acp into the truck door – none pierced. He pulled his back-up 357Sig, and with one round – the fight was over !! It loks like the 45acp is now in a close, but second place – - – !!

    • Steve says:

      Actually Dano, the 357 SIIG round was fired by the senior officer’s rookie partner who as a new officer had been issued the new weapon and round of choice of the Texas DPS, the 357 SIG. The rest of the story is quite accurate. The 45 failed to penetrate the cab of the tractor, but the 357 SIG round penetrated the cab and then the head of the driver putting a stop to the fight. At least that is the way the story goes here in Texas.

  21. S'S Mark says:

    I have
    Been reloading and shooting the 357 sig for about 3 years. I love the Round it’s fast very accurate and easy to reload. Look up reloading blogs on the Round the is an easy 2 step sizing process. I use 8.5g of Longshot for moderate load at 1350 though a Barsto 5.3′ barrel. One inch groups at 25 yes on good days.

  22. Ron Reed says:

    Finally im in good company. I was first turned on to the sig 357 round in 1998. I was hired as a deputy sheriff fancy word for saying i was a jailer, but at that time the sheriffs office i was hired at were using sig 229 chambered in 357 sig. We still carried are weapons during transports so we had to qualify like the rest of the road officers, i fell in love immediately. Im now a firefighter / Paramedic but have kept up with my love of owning and shooting the sig round. I dont leave the house without my glock 32 with a mag full of underwood ammo. Just recently i tried out for our local police department swat team as a tactical paramedic, i consistently shot a 250 when qualifying with my glock 32, in fact i turned a few heads and got some talk brewing with the officers about this paticuar cartridge.

  23. . Simple fact: in a semi-compact pistol like the P229 the .357 SIG offers better accuracy and more power than either the .40 or the 9mm. Wiley Clapp’s review suggests that it does indeed equal or better the ballistics of the mighty .357 magnum. Loss of pressure from the cylinder-frame gap may have something to do with that.In any event, Clapp’s findings debunk the oft-repeated claim that the .357SIG does not equal the magnum’s performance. With so many shooters believing this claim, it might have been better if the SIG marketing mavens had named their new cartridge the SIG 9mm Magnum. That’s really what it is, and it does a great job of being just that.

  24. Mark says:

    I have been hooting this round for bout 5 years. I have glock model 35 with barsto barrel conversion and a Model 24 with a Barsto barrel Conversion. I can get 1,600 FPS with Underwood 124 grain 357 sig Ammo from the model 35, One inch groups Rested at 25 yards. That’s thumping most 4′ 357 magnums. My load of choice.

  25. craig says:

    Please correct me if I’m wrong. I recall a 200 grain “bone crusher” bullet for the .357 magnum.

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