How does the .357 auto compare to the 357 mag?


June 25, 2004, 08:17 PM
My friend has the springfield xd-40 and is thinking of swapping barrels to the 357 auto.

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June 25, 2004, 08:39 PM
.357sig I assume? It throws a ~124 grain at ~1400 fps. About the same as the SD .357 mag loads. True top end .357mag can do a lot better though.

June 25, 2004, 09:11 PM
The more or less standard (or certainly at least most common) load in the 357 SIG is 125-grain bullet at about 1350 - 1400 fps. The .357 Magnum shoots 125-grain Gold Dot 1603 fps (factory ammunition) out of a four-inch barrel.

There really is no comparison. The 357 SIG (really a 9mm) was called "357" for marketing purposes to attempt to capitalize on the reputation of the .357 Magnum. The .357 Magnum can handle a far greater range of bullets weights and at considerably higher velocities (for example, the .357 Magnum shoots a factory 158-grain bullet faster out of a four-inch barrel than the 357 SIG can 125-grain bullet). The only autoloader that falls within the .357 Magnum performance window is the 10mm with hot loads--for all practical purposes the .357 Magnum and 10mm are ballistic twins. So, how does the real question probably should be 357 SIG compare to the 10mm (since they are both autoloaders)?

June 26, 2004, 12:22 AM
I was surprised to find the smaller alloy frame pistols that holds up so well in the 357 sig, one being the Sig 239. Rate of delivering bullets has alot to do with the popularity of the 357 sig, and the fact that it is usually chambered in the smaller, lighter, pistol frames that is often shared with the 9mm. The purpose of the 357 sig is not to duplicate the full potential of the .357 magnum, but to offer an optional choice to the .40 S&W, using the same slide, breech face, ejector, extractor, magazine, and springs in most applications, using only a drop in conversion barrel.

June 26, 2004, 01:00 AM
A LOT of factory .357 Magnum loads are watered down, as people don't like firing the hot stuff out of K-Frames that get rattled out of time and airweight J-Frames that split the web of your hand.

It's gotten to the point where a lot of people consider a 125 grain bullet at 1450 feet per second to be a super "hot load" for .357 Magnum. Now, I haven't shot a lot of .357, but if you look at reloading manuals and see what .357 can really do, you'll find that 125 grains at 1450 really isn't all that hot. (If you think it is, trying doing that same velocity with a 210 grain bullet through a .41 Magnum. Now that's entertainment!)

Of course, I've heard that these .357 loads generate excessive amounts of noise and flash. Perhaps they feel hotter than they are?

In any case, .357 Sig is marketed as duplicating the ballistics of these mid-range 125 grain .357 Loads, which it does well enough, from what I've read. I've heard that .357 Sig guns have shorter service lives than comparable .40 models, but it's second or third hand information.

In terms of raw power, though (pushing the heaviest bullets to the highest velocities), .357 Magnum spanks .357 Sig quite handily.

However, 158 Grains at 1400 feet per second might be too much recoil for you, or another shooter. There is a point of diminishing returns, where recoil becomes so great as to actually hamper shootability. For me, .41 Magnum and warm .45 Colt are perfectly comfortable, as is .45ACP +P and Super. For another, 125 grains at 1400 feet per second might be all the oomph they're comfortable with.

I've heard that the 125 grain .357 loads sometimes fragment and don't penetrate deeply enough, and the same consideration thusly applies to .357 Sig. However, given proper bullet construction (or, as a last resort, use of full metal jacket ammunition) this wont' be a problem.

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