.357 Magnum: The First of the Magnums

This Cartridge Was Born Of A Quirk Of Ammo History & A Writer's Tenacity

Sometimes, something that’s pretty good gets tweaked, and something far different is created — something potent. When gun writer Elmer Keith teamed up with Phillip B. Sharpe of the National Rifle Association and Douglas Wesson of Smith & Wesson, they built the first magnum handgun cartridge. The .357 Magnum is still revered for its terminal ballistics and shootability 90 years later. 

The .357 Magnum was developed in stages by a group of people in the 1930s, first as a wildcat cartridge loaded by Elmer Keith and then as a commercial ammunition round developed by S&W. The commercial push was a response to Colt’s .38 Super Automatic. At the time, organized crime had been strengthened by more than a decade of Prohibition, and the level of violence associated with it had also been elevated. Plus, the 1920s saw automobiles become a crucial tool in both the commission of crime at all levels and for police. 

The .38 Super was the only American handgun round that could reliably put holes in the heavy skin of automobiles of the day, as well as early bulletproof vests, which some criminals were fond of using at times. They could withstand any handgun round moving slower than 1,000 fps, so the fat, slow .45 ACP wasn’t getting through. The .38 Super moved at just a bit faster than 1,000 fps, so it got through most of the time, giving police a valuable tool. 

The .38 Special, introduced in 1898, served as the parent case for the .357. Elmer Keith identified it as an ideal candidate because the .38 was developed at the end of the black powder cartridge era — the first loads on the market were indeed loaded with black powder, though it was soon transitioned to smokeless powder. 

This mean that there was a ton of room left in the case with more dense modern propellants — the .38 could be pushed quite a ways further. For context: the 9mm Luger rounds, introduced in 1902, were made for smokeless powder and the consequent higher pressures. It produced a lot more energy than the .38 even though the case is less than half the size.   

While the calibers have different names, both the .38 Special and the .357 Magnum have the same diameter bullet — the only external difference is case length — and that difference was intentional so that .357 rounds couldn’t be accidentally loaded into a .38 Special revolver and blow it up — more on that later. 

That’s why any .357 Magnum revolver or lever gun can also run .38 Special ammo, but not the other way around — it’s analogous to the .44 Special and the .44 Magnum, the latter of which came along in the 1950s.  

The .357 didn’t need any additional case volume, since the .38 Special was first developed as a black powder load and there was plenty of room with denser modern propellants. 

Elmer Keith’s Wildcat .38-44 Loads

One of the best minds in the area of handgun cartridges was famous hunter, writer, and wildcat experimenter Elmer Keith. He was determined to push the .38 Special to its limits by creating increasingly higher pressure loads. That’s great, but why would guns exist that could handle that pressure?

There were a few Smith & Wesson revolvers at the time that were heavy, target models like the S&W .38-44 “Heavy Duty” and “Outdoorsman,” which were built on oversized .44 Special frames and barrels that were instead bored for .357-caliber bullets and matching cylinders for the .38 Special - .3801 - .3809 inches in diameter, hence the cartridge’s name. They could handle the pressures Keith was cooking up with his handloads.  

The .38-44 HV load Keith invented typically generated chamber pressures equal to that of a .357 Magnum. It was essentially the prototype of the new Magnum load — all that was left was to lengthen the case for safety, as mentioned before. Keith’s .38-44 cartridges would absolutely fit in a .38 Special — likely with catastrophic results. 

But that wasn’t all Keith contributed on the road to the .357 Magnum — he created the “Keith-style” bullet, which was designed to increase the mass of the bullet located outside the cartridge case to maximize space inside the case for propellant.  The bullet also featured a broad, flat meplat, which caused significant damage to the target without deforming like a hollow point, and it was, predictably, great for hunting. It also made a good target bullet, like a wadcutter.  

The .357 Goes Public

When it came time for Keith’s new round to be commercially produced, Smith & Wesson stepped up to help reinforce its reputation as the premier provider of law enforcement gear and firearms — the .357 Magnum had great potential as a police cartridge that was powerful but with manageable enough recoil that almost any officer or agent could shoot it effectively. And if they couldn’t, they could always load their .357 Magnum revolver with .38 Specials. 

S&W essentially did what Keith did, with the help of Sharpe from the NRA’s technical division — it created the new .357 Magnum from its existing .38 Special round. A different powder load was cooked up and the cast was lengthened by 1/8 inch (3.2mm). 

It’s worth noting that Colt New Army revolvers in .38 Long Colt, if you happen to have one, can physically chamber both .38 Special and .357 Magnum — dangerous since the .38 Long Colt was notoriously underpowered and both rounds would create many times the pressure the revolver was built for. In other words, boom.  

.357 Magnum Cartridge Specs

The first S&W .357 Magnum load had a 158-grain bullet moving at an advertised velocity of 1,525 fps — they ran hot in the 1930s. The muzzle velocity on today’s recommended loads for most uses is about 1,500 fps. 

That’s from a handgun with a barrel about 7 inches long. In a rifle, the .357 can move about about 1,800 fps, making it ballistically superior to the .30 Carbine, for context. Thanks to this, the nice rim on the casing, and its tame recoil, the .357 has become a popular chambering for modern lever action carbines and rifles.  

While law enforcement moved away from the .357 to the 9mm when revolvers gave way to semi-autos, they don’t match the .357 Magnum in power — that’s why the rimless .357 SIG was developed and the lesser known 9mm Winchester Magnum. 

.357 Magnum: The Guns

The large frame Smith & Wesson Model 27 came along in 1935 and was the very first firearm chambered for the new .357 Magnum. Ever since, the round has been used for all sorts of applications: hunting, silhouette target shooting, self-defense, and law enforcement. It has been used as a dangerous game round against animals as large as bears, though most would recommend something more significant for that purpose. But in the 1930s and 1940s, there wasn’t anything much bigger on the commercial market. 

Today, when compared to larger magnums like the .44 Magnum, .460 S&W, and .500 S&W, the .357 doesn’t have as much energy, but the smaller bullet and the round’s high velocity means it penetrates very well. Plenty of hunters use the .357 in a long-barreled revolver or a lever gun for deer hunting at appropriate ranges to great effect. 

It hits game much like the .45 Colt, but with a flatter trajectory thanks to the velocity. 

In recent years, Colt reintroduced its popular DA/SA Python revolver line chambered in .357 Magnum with a few finish and barrel length options. 

S&W, the father of the cartridge, currently has 44 revolvers in its catalog chambered for .357, including J-, K-, L-, and N-frame models. Oddly enough, it recently entered the lever gun space, but only currently has .44 Magnum and .45 Colt chamberings for its Model 1854 rifle. 

Henry offers several .357 models in its popular Big Boy line, including its All-Weather and X Model series.

Ruger offers three of its 77 Series bolt action rifles chambered in .357 Magnum, which is interesting. It uses a 5-round rotary magazine to reliably feed the rimmed cartridges. Almost all of Ruger’s popular revolvers models are offered in .357.