357 Sig. What Makes This Cartridge So Great?

Everything You Need To Know About .357 Sig

If you're waiting for .357 Sig to make a comeback...I wouldn't hold my breath. However, if you're curious about it, let's learn what there is to know about the round.

There are intermittent flare-ups of interest in .357 Sig, almost like the recurrence of a chronic disease, and folks get curious. While it has some impressive attributes on paper, the reality is there are more drawbacks than benefits, and the benefits aren't so dramatic that it merits a caliber change in the real world.

So, without further ado, let's get into the 5 Ws of 357 Sig.

What Is 357 Sig?

357 Sig is a proprietary cartridge developed by Sig Sauer.

Sig Sauer's goal was to replicate a 125-caliber .357 Magnum load (with a rough muzzle velocity of 1,450 feet per second) in a semi-auto pistol without the requirement of a large-frame pistol.

The .357 Sig cartridge was developed in in conjunction with the Federal ammunition company. To achieve the attributes that Sig Sauer had in mind, Federal cut a 10mm case back and necked it down to 9mm caliber. Much like many rifle cartridges created in a similar way, this puts a 9mm bullet over more powder.

Since it's roughly the same size as .40 S&W, .357 Sig can be used in pistols with a frame built around 9mm.

Contrary to popular belief, 3.57 Sig is not a necked-down .40 S&W. The overall length of .357 Sig (1.14 in) is about 0.009 inches longer than .40 S&W. It also has a teeny bit more case capacity (19.6 grains vs 19.3 grains) but not so much that it really matters.

Initial factory loadings were close enough, and a number of current 125-grain .357 Sig loads still do.

The first .357 Sig pistols emerged soon after, being offered in Sig Sauer's (then) core models like the Sig P226, P229, P228 and so on.

357 Sig Ballistics

While 357 Sig seems to have impressive ballistics on paper, it has costs. It's far harder on pistols, wearing out recoil springs and other small parts much faster. It's harder on shooters, with harsher recoil than 9mm. It's more expensive. As a result, law enforcement didn't adopt it in huge numbers and it barely achieved a toe hold in the civilian market.

But what does it do well?

A 125-gr .357 Sig achieves muzzle velocity in the neighborhood of 1400 to 1475 feet per second, and muzzle energy in the neighborhood of 580 to 620 ft-lbs of energy with most standard pressure loads and a 4-inch barrel, roughly equal to a 125-grain .357 Magnum load fired from a 4-inch barrel.

Unlike other autoloading .38 caliber cartridges (such as .38 Super, 9x23mm Winchester and 9x25mm Dillon) it's sized for use in a pistol frame designed for 9mm.

When loaded with expanding projectiles, .357 Sig gets (the story goes) the best out of 9mm projectiles. Since hollow point performance is velocity-based (below expansion threshold, nothing happens, above it and the bullet goes to pieces) expansion with quality hollow points is reliable and dramatic. The notion is that a 9mm projectile will penetrate more deeply and expand wider and more reliably from a .357 Sig than a 9mm...

...in theory.

.357 Sig vs. 9mm Terminal Ballistics

None of the respected sources of ballistic testing such as the former International Wound Ballistics Association, experts such as Dr. Martin Fackler or Dr. Gary K. Roberts, found .357 Sig to be any "better" than 9mm.

Lucky Gunner Labs tests found only a marginal increase in penetration and expansion compared to 9mm.

Lucky Gunner uses a gel testing protocol similar to the FBI's ammunition test which puts the bullet through 4 layers of denim into a gel block.

Their testing found 135-gr Hornady Critical Duty had equal penetration and a 0.04-inch increase in expansion for .357 Sig compared to 9mm. The 124-grain 9mm Gold Dot load outpeformed the 125-grain .357 Sig load dramatically, with 18.1 inches penetration (compared to 13.2 inches for .357 Sig) but the .357 Sig loading expanded to 0.67 inches on average vs 0.54 inches in the 9mm load. Federal's 124- and 125-grain HST loads were near as makes no difference identical.

In other words, what testing is available indicates there's no real advantage.

Some contend that .357 Sig exhibits hydrostatic shock, which is totally and patently false. No handgun load propels the bullet fast enough (with enough kinetic energy) to actually produce hydrostatic shock; it doesn't happen with any projectile traveling slower than 2,000 fps with 1000+ ft-lbs of energy at minimum. Even the much-ballyhooed 5.7mm doesn't produce hydrostatic shock; it only occurs with rifle cartridges, has always only occurred with rifle cartridges and never, ever, will be a thing with a pistol bullet.

Nothing emerged in terms of any department that issued it finding any cause for dissatisfaction, including the US Secret Service and Federal Air Marshals, and some metropolitan agencies found it was very effective against aggressive dogs.

So is.357 Sig effective? Yes. Is it the DEATH RAY THAT PEOPLE SAY?! No. It's just a hot 9mm.

.357 Sig Ballistics In Greater Context

Be very careful drinking the Tactical KoolAid of .357 Sig, 5.7x28mm or indeed any handgun round. A lot of people believe fantastical things about what pistol bullets actually do, and the reality is that pistols only poke holes in things. Pistols, as Tom Givens says, are basically cordless drills.

What has been established over the years is that absent ammunition failures and failures of marksmanship, most handgun rounds are near as makes no difference equally effective when placed properly. In other words, it makes little difference if you carry a 9mm, a .357 Sig, .44 Magnum or a .45 ACP. If you've carry quality ammunition, load it in a pistol you can shoot, and put it where it needs to go in a person that is threatening your life, it will do what needs to be done.

Placement and penetration are the lion's share of lethality.

As mentioned, it was found to be very effective on aggressive dogs so it may have some potential as a woods round so long as you don't have to worry about brown bears. Granted, it should go without saying that a rifle or a shotgun is always a better bear gun!

Aside from that, there has never been - to date - any published evidence (not anecdotes or conjecture; evidence) that .357 Sig does anything better than 9mm, except for putting wear and tear on police pistols and costing more.

What's The Best .357 Sig Pistol? Can You Get A Sig Sauer .357 Sig Anymore?

best .357 sig pistol

.357 Sig is dying and/or dead. The only major gun company still making pistols in this chambering is Glock.

Therefore, the two best pistols of current production are the Glock 31 and the Glock 32. These are the .357 Sig equivalent of the Glock 17 and Glock 19, respectively.

There is also the Glock 33, a subcompact (a Glock 26 in .357) if you like suffering.

Sig Sauer does offer Caliber X-Change kits for P320 Compact and P320 Carry pistols. You just have to swap in your current Fire Control Unit from your existing P320 pistol.

Aside from the Glock .357 Sig pistols, you'll have to dip into the used market. There's no definitive "best" among them, but there are some very good choices.

The original Sig Sauer .357 Sig pistols make a good case for themselves, especially the Sig P226 and P229. The Sig P228 and P239 are out there as well. They are reliable and can handle the .357 Sig round with ease.

There are a small number of .357 Sig 1911 pistols out there, mostly Sig Sauer 1911 pistols. Smith & Wesson had a brief run of M&P357 pistols, and H&K likewise made USP Compact and P2000 pistols chambered in .357 Sig though in small numbers.

If one had to select from the used market, the P229, P226, and USP Compact would be the best. The S&W M&P357 would also be a decent choice, as the M&P series was designed for the ground up for .40 S&W rather than 9mm.

357 Sig Drawbacks And Pitfalls

There are a few known drawbacks of .357 Sig, and if you're curious about the cartridge, these are the pitfalls that you need to know about.

Internal .357 Sig ballistics are more violent than .40 S&W and 9mm.

Chamber pressure of .357 Sig ammo is typically 40,000 to 44,000 psi, more than 10,000 psi more than 9mm (typically 33,000 psi) and .40 S&W, which is typically around 35,000 psi.

The additional slide velocity and chamber pressure put mroe wear and tear on the gun, meaning even the best .357 Sig pistol is going to take a beating. .40 S&W pistols are already known for shorter life cycles, as are 10mm pistols (for those same reasons) and it's a contributing factor in why so few agencies adopted and kept issuing .357 Sig pistols.

Granted, few gun owners shoot enough to wear out any gun so perhaps that isn't the greatest concern, but is a known quantity.

Sheer cost is another factor. Typically, .357 Sig ammunition is about double the cost of 9mm ammunition if not more, and is rarely found on store shelves. You can shop online, of course, but even then selection is still not as good as 9mm, .40 or .45.

Available pistols is another consideration. Glock is the only company still making them; Sig Sauer has dropped it entirely...and they invented the cartridge. That's what we call "a clue."

Don't even bother asking about a P365 in .357 Sig. They won't, and we know this for a fact because Phil Strader (Sig Sauer's product manager for firearms) told us point-blank at SHOT Show 2019 that "we'd make one in .45 ACP before .357 Sig, and we aren't ever going to make one in .45 ACP."

Then there's the recoil. A .357 Sig pistol that weighs about 2 lbs, firing the classic 125-grain load, will generate something like 9 ft-lbs of recoil, roughly double that of 9mm though slightly less than the recoil of a .40 S&W pistol of that same size and weight firing the classic 165-grain and 180-grain loadings.

Is it a bad cartridge? Not at all. It's a hot 9x19mm, and 9x19mm is the global standard for good reason. It's just that it doesn't do anything so much better than anything else that it's proven itself to be worth it to most police departments and to most people.

But, it does have its fans, and that's fine.

12 Comment(s)

JackD

Oct 24, 2023 17:44

This post is pretty much the same as one on Lucky Gunner, and both are based on gel tests. Let me explain the problem with gel tests in comparing .357 SIG with 9mm.

We are talking about two very similar projectiles in terms of weight and diameter. One is moving 300 fps faster than the other. Yet they have similar penetration and similar expansion. How can this be?

The explanation is, gel is gel. Gel does not have ribs. Gel does not have hard and soft parts. Gel is uniformly pretty soft.

It is a good medium for certain types of testing, but it should not be assumed to be a good representation of an animal's body.

If you find Paul Harrell's video about choosing .357 SIG personal defense ammunition, and fast forward to the "meat target" portion near the middle of the video, what I am saying will suddenly make sense. Better yet, compare and contrast it with his "meat target" test of 9mm.

To explain briefly what you will see (and I am focusing on the cartridge most people would pick for defensive carry use, Speer Gold Dot 125gr JHPs), the "meat target" is t-shirt, leather, pork meat, pork ribs, fruit to represent lung tissue, more pork ribs, more leather, and more t-shirt, with a fleece layered bullet stop behind it. Compared with 9mm, .357 SIG does much more damage to the first set of ribs, blasting large holes in them that you can fit two fingers through. It does more damage to the "lung tissue." By the time you get to the back ribs, it has lost most of its power. It goes through the ribs the way 9mm does, and gets stuck in the t-shirt or first layer of fleece.

In summary, you get more damage to the intended target, without overpenetration. As for the "why", let's go back to the part about .357 SIG having an extra 300 fps of velocity. All else is more or less the same. That extra 300 fps results in a more violent impact and more violent expansion. That results in more initial damage. But once that is done, the projectile settles down and behaves more like a 9mm. The extra 300 fps went into making bigger holes in the ribs and shredding the lungs more. Once it has done that, it is down to the same approximate level of the 9mm.

In real-world use, this means a round of .357 SIG is more likely to incapacitate an attacker than a round of 9mm, without greater risk of overpenetration.

Until you are attacked by blocks of ballistic gel, this stuff matters. Most attackers have ribs and lung tissue and are not simply blocks of gel, or any equivalent such as a walking blob of fat or muscle.

And let me add a caveat in case anybody misunderstands: .357 SIG is not the most powerful round, by any means. I could list quite a few that are more powerful and tend to do more damage to animals. However, .357 SIG is more powerful and tends to do more damage to animals than 9mm, or most of the other popular options. It tends to do more damage to animals than .40 S&W or .45 ACP, for example. To beat it, you would need to step up to 10mm or .357 Magnum, and even that is load-dependent.

Of course, rounds like .44 Magnum or, say, 454 Casull will be more damaging, but they are in a different realm as far as the types of handguns you would use, recoil, muzzle flash, etc.

I am not recommending that you switch to .357 SIG. I am recommending that this blog and other sites stop misrepresenting gel tests as being definitive or telling the entire story.

Todd tee

May 23, 2023 01:44

Sig p228 is a 9mm only gun
P229 is a multi caliber handgun
Writer of article seems to not use REAL hot
357s loaded ammo.
It’s like saying 10mm is not a worthwhile cartridge while using Winchester white box to test with.

357s is fast, and with 1450 plus fps comes lots of energy out of a 125g bullet. This round was designed as a barrier penetrator, which author did not discuss.
9mm rounds tend to glance off of windshields. 357s will continue straight.
I am a big fan of 357s. And edc it.

Alex

Oct 19, 2022 17:21

As someone who shoots in a club every weekend, the 357 Sig is my favorite round. I own a Sig 2022, Sig P229 and Glock 22 all which shoot the round with high precision and reasonable recoil. It’s a round that shouldn’t be forgotten by ammo manufacturers. In 2022 it’s becoming more difficult to find new Ammo, except hollow points. BTW, I paid $300 for my used 2022, which is an awesome deal for a quality handgun.

Tom

Sep 09, 2022 19:52

P228 was always and only a 9mm pistol

Derek Smuin

Jun 14, 2022 22:02

Well, Sig makes a P320 in .357 sig and 45, so pigs do fly.

Pearson Harold L.

Jun 06, 2022 06:59

I think you missed the entire boat with this article. The boat even left before you got there. It is the devastating shock power you get with a well made”90” grain bullet. That is so impressive. 1850 Feet Per Second
Muzzle Energy 684 Foot Pounds of shocking energy made by Grizzly ammunition.
I once shot a rabbit with that round and the rabbit literally exploded. But that is neither here nor there. Just look at the gel test with “that” round.

John Mott

Aug 07, 2022 07:48

I shot a rabbit with a 125 grain 357 Sig from about 15 feet back in 2008 coming off of the deer stand and the only salvagable meat were the legs. The rest did as you said and basically "exploded".

Oct 24, 2023 18:37

I like looking at gel tests. I find them meaningful, but only within specific aspects of comparison.

We know that .357 SIG and 9mm have the same projectile diameter and generally similar weights. We also know that .357 SIG is higher velocity. So when we look at a gel test that shows similar results, does that mean the difference in velocity doesn't matter? Or does it perhaps mean the gel test doesn't cover everything?

Many of us know the answer from real-world use (I am mainly, but not exclusively, referring to hunting). But for others, Paul Harrell's "meat target" is the best simulation I have seen.

Harrell is not especially a .357 SIG advocate, but he tests .357 SIG (various brands and types) in the same way he tests various brands and types of other popular cartridges including 9mm, and we can compare how they perform against things like t-shirt fabric, leather "skin", pork chop "pectorals", pork ribs, and fruit "lungs." And what we find is that .357 SIG is more damaging to the "pectorals", the first set of ribs, and the "lung tissue." It is no more damaging to the back ribs and it does not penetrate further. What this tells us is that the difference in velocity gets used up shattering ribs and shredding lungs, after which we're left with a similar size projectile with similar remaining energy. In gel, the difference in energy appears as temporary stretch cavity and is discounted by many writers who only know gel tests. But in an animal body, it isn't merely temporary stretch cavity, it is smashing ribs and shredding lungs.

A little knowledge is a dangerous thing, and people with a little knowledge from gel tests pontificating about this round are the reason it's a "dying caliber." By the way, I agree its popularity is declining. That does not mean it's not a good cartridge, though, and perhaps at some point, writers will think this through without people like me needing to explain it in the comments section.

JIm Postell

Jan 30, 2022 08:06

Poorly written article. Most 357sig rounds clock at 1350fps and 506ft/lbs, not at true 357mag performance of 1450fps and 584 ft/lbs. The latter, in a semi-automatic (like Underwood loads), is a formidable combination and a full step beyond ordinary 9mm for those who can shoot it accurately. There's no way gel testing and real world won't reveal a big difference between commercial 357sig loads and those possessing true 357mag performance.

Bill

Nov 16, 2022 11:12

Exactly. The author of this article is either a 9mm apologist or just doesn't know what he's talking about, which I think is the case. I shot a full grown groundhog from 50 feet and, it too, basically exploded. Instant death. As for recoil, the 357 Sig recoil is less than a 40 cal Beretta I've shot so anyone saying it's punishing or excessive should stick to a 22 cal handgun. The 357 Sig is a fantastic caliber and the people that jumped on the 40 bandwagon early on should have buyers remorse as that caliber has fallen way out of favor to the "guess what"? 9mm. The 357 Sig is a 9mm on steroids.

James Hamblen

Jan 16, 2022 17:20

The 9 mm and 45 acp had their day. Why is it when something new comes along it's eventually put down. You say that the 357 Sig. is no death ray. Neither is the 9mm or 45acp, matter in fact there light-years from it!

Chris Stroud

Jan 22, 2022 13:02

When something new comes along, if it OUT PERFORMS something existing, in the categories in which the existing round has already (for decades) been embraced, AND enough manufacturers develop competitive (cost & performance) platforms for sale, it doesn't get put down. .357 Sig did not offer anything you couldn't already get, no mindblowing differences in the accepted categories but more importantly, not enough platforms. If Sig Sauer won't make weapons for a caliber that bears their name, why would anyone else? Yes, there's Glock, but who else is going to make that leap? Death Rays don't exist. Proper employment of the weapons' system and correct targeting do, and if your weapons system is a .32 ACP and you know how to employ it and target it correctly...then it's a "death ray". 9mm and .45 ACP had their day...it's never sunsetted. You're living in their day.

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