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Old May 17, 2013, 09:01 AM   #1
kirbinster
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.357 magnum VS .38 spl question

I recently purchased a S&W686+ 4" stainless and love my new revolver. The first day I tried it I used some .38 special and said to myself wow this thing feels like shooting a .22 - almost no recoil just a slight push. The next time out I tried some .357 magnum and wow, the thing kicked and I really felt it in my hand. So, my question is how can there be so much difference in these two rounds that are the same diameter and only differ in length by roughly 1/10th of an inch. Both sets of rounds were from the same manufacture and were both 158 grains - so how do they stuff so much more power into that 1/10th of an inch? I looked up the energy difference and the .38spl is rated at 285 while the .357 mag is shown as close to double that at 548.
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Old May 17, 2013, 10:12 AM   #2
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Other than that 1/10th of an inch, and different SAAMI pressure (35,000psi max for .357 and 17,000 psi for the .38) Not a hell of a lot. People will tell you .357 mag uses magnum primers but that really depends on the powder. I haven't reloaded any .357 but I'm assuming it could be a compressed powder charge that garners the extra oomph

** EDIT: Type of powder also matters greatly! The same grains of a different type can produce wildly different results
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Old May 17, 2013, 10:33 AM   #3
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The slight difference in length is just a safety precaution, nothing to do with power. Its there to simply prevent .357 magnum ammunition going into .38 Spl. chambers which would be a disaster. The .38 Spl. is actually a black powder round originally so the case is huge for most modern smokless powders because of the large difference in energy available per grain burnt.

The real difference is internal, & not easily visible, its the type & volume of powder used & the pressure levels it works at. As an example a .38 Spl runs about as hot as is sane with 4.8 grains (a grain is 1/7,000 Lb, so thats a very small amount) of powder & pushes the bullet at 930 Feet per second, it generates about 15,500 CUP of pressure. Now a .357 Magnum can go as high as 22.0 grains of powder pushing the exact same bullet at 1,966 FPS at a pressure of 41,400 CUP of pressure.

Different types of powders are used as well, essentially fast (for rifles) powders are considered "slow" in a pistol & are harder to ignite reliably, so the "magnum Primer" function is just to give a bigger spark to get the slower powderrs such as H-110, or 2400 burning. If you use powders like "Titegroup" for example you can safely run standard pistol primers & still get higher velocities from .357 loads.

As you can imagine the difference in recoil will be considerable because of every action having an equal & opposite reaction! If you ran the .357 Mag load's 41,400 of pressure in a gun designed to handle 15,500 the result would be catastrophic, so the safety of making it impossible to make that mistake is needed!
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Old May 17, 2013, 11:05 AM   #4
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kirbinster,

In the .38 world, many different animals exist. For instance, you may have been using a standard pressure .38 when you first fired your new gun. Not
much recoil. But had you used .38 Plus P (Plus Power) rounds, the recoil would have been a bit more. The .38 can also be loaded as a target load, even less recoil than a standard .38 Special Lead Round Nose in 158 grain.

By using a 158 bullet in your as a .357, you were probably getting about the maximum kick for that round. But had you had a .357 in say 125 grain jacketed hollow point, the recoil though still "hot" would have been less.

I suggest you take a look on the Internet at the Winchester or Remington sites for the kinds of .38s and .357s they produce and you'll get an idea of power factors and foot pounds. And among the ammo makers rounds are produced specifically for certain barrel lengths and weights of guns, i.e. the
J-frame Smiths, the K-frame Smiths.

Normally for home defense and carry the .38 Plus P is considered a decent round in around 125 grain jacketed hollow point or 158 grain lead semi-wadcutter hollowpoint.
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Old May 17, 2013, 11:42 AM   #5
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Velocity. Your 38 spl was probably going about about 750 fps and the 357 mag about 1250 fps. I use 38 spl +P for HD just to try and minimise over penetration.
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Old May 17, 2013, 11:52 AM   #6
orionengnr
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As stated in post #2, the big difference is pressure.
Quote:
(35,000psi max for .357 and 17,000 psi for the .38)
That pressure translates into velocity and energy. Newton's Third is vividly portrayed, and the results are what you noted.

As was also mentioned, most of that case capacity is wasted. A 9mm has a similar diameter case and a much shorter length. However, the 9mm uses most of its case capacity, and the resulting pressure/energy of a strong 9mm steps into the neighborhood of the .357 Mag.

Where the .357 flexes its muscles is in its ability to utilize a wider variety of bullet shapes and weights, especially at the heavier end of the bullet spectrum.

Lots of good info and informed folks on this board. And they are always willing to share.
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Old May 17, 2013, 12:12 PM   #7
James K
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Question asked: "how can there be so much difference [in recoil] in these two rounds that are the same diameter and only differ in length by roughly 1/10th of an inch"?

Question answered: ".38spl is rated at 285 while the .357 mag is shown as close to double that at 548."

Mr. Newton says energy in one direction equals energy in the other.

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Old May 18, 2013, 06:54 AM   #8
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They can stuff enough powder into the 38 case to get almost the same power from the 38 round. They just choose not to do so. Prior to the 357 magnum it was not uncommon for companies to load HOT 38 special loads with instructions to only load them in heavier large framed guns. There was even a load labeled 38/44. This was simply a hot 357 equivalent load, but in a 38 case. It was intended to only be loaded in 38 guns built on a 44 Special frame.

But too many people started buying this hot ammo and put it into weaker guns and causing problems. The 357 load was developed and made 1/10" longer to provide the power of these hot 38 loads, but it could only be loaded in guns made specifically for it.

Back in the 1970's-80's it was common for many police depts. to carry 357 mag revolvers, but many local governments took a dim view of them carrying the politically incorrect, too powerful 357 round. Ammo companes responded with 38+p+ ammo loaded to near 357 mag specs. This gave cops 357 mag perfromance, and city mayors could tell their citizens that their cops were not allowed to carry 357 mag ammo. Everybody was happy.
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Old May 18, 2013, 06:27 PM   #9
s4s4u
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Quote:
So, my question is how can there be so much difference in these two rounds that are the same diameter and only differ in length by roughly 1/10th of an inch.
SAAMI

Manufacturers load to SAAMI specs. SAAMI is conservative to protect older firearms, and their users, from damage. This is why the +P designation was created. You can hand-load 38 Special to a level approaching factory 357 Magnum performance, for use in appropriate firearms. Such is also the case with 45 Colt, which can be hand-loaded beyond 44 Magnum performance, but could destroy some older firearms chambered in 45 Colt, SAAMI sets the limits.
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Old May 18, 2013, 11:34 PM   #10
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The difference is the 357 is loaded to twice the pressure as 38 Spl. as per their specifications.
The 38 Special came to be at the very tail end of the black powder cartridge era in about 1899 and was about the last black powder cartridge ever developed. That's why the case is so big. It was originally filled with black powder. There is a very small amount of the much more powerful smokeless powder in the large case as is today to keep it under the pressure spec.
The 38 Spl. is a wonderful cartridge for the reloader. So very easy to assemble, very versatile, accurate, and safe.
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Old May 19, 2013, 08:24 AM   #11
kirbinster
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Thanks for the feedback.
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Old May 19, 2013, 09:35 AM   #12
22-rimfire
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I think your focus on case length is what has colored your impressions and expectations. Parisite addressed the black powder versus smokeless powder issue and that is pretty much the reason for the case length. This is really important.

Quote:
Both sets of rounds were from the same manufacture and were both 158 grains - so how do they stuff so much more power into that 1/10th of an inch?
The 357 was designed using smokeless powder and the increase in case length was done so that revolvers chambered for 38spl would not accept the longer case. Safety. The same approach has been done with some of the 44 caliber offerings and why you normally find 45 Colt loaded rather tamely in factory loadings.

There tends to be a lot of talk on the forum(s) about the 44 magnum and shooting it. Many, especially inexperienced shooters, seem to dismiss the 357 mag from a recoil point of view. But the 357 mag IS actually a pretty powerful cartridge and one that you need to learn to handle the recoil when shooting it especially in the heavy bullet weights. 38spls tend to be loaded pretty tamely and the 357 mag loads tend to approach maximum loads relative to SAAMI pressures. I would assume that's market driven and the fact that you can shoot regular 38spl and 38spl +P's in the same 357 mag revolver, so you get tremendous variety.

Last edited by 22-rimfire; May 19, 2013 at 10:51 AM.
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Old May 19, 2013, 10:18 AM   #13
newfrontier45
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We must also remember that the early smokeless powders were also very bulky. So even if it had been designed for the early smokeless powders, the case still needed to be capacious.
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Old May 19, 2013, 10:58 AM   #14
22-rimfire
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I was going to add this to my previous post and changed my mind.

I find it interesting how the 357 mag was marketed in its early days and some people using it for hunting dangerous game and protection from 4-legged predators. It really was a powerful cartridge for the time.

Now the predator protection issue usually goes to 44 magnum for the most part. Folks in black bear country offen use the 357 mag for that purpose but where bigger bears are present, the argument usually goes to 41/44 magnum or more powerful these days.
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Old May 19, 2013, 11:12 AM   #15
Jim March
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Quote:
(35,000psi max for .357 and 17,000 psi for the .38)
The older spec for 357 called for 43.5k max, and there's a few smaller more radical ammo houses still loading some of their hotter stuff to that point - Buffalo Bore, Underwood, probably Grizzly Cartridge and DoubleTap.

It's not called "357+P" but you can sort of think of it that way.
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Old May 20, 2013, 05:39 AM   #16
foghorn25
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I like the compromise of shooting +Ps. It doesn't feel like a pop-gun but it won't make your hand go numb after 12 rounds either. Also training-wise your closer to the "feel" of a .357 load without having quite the "expense" of the more costly ammo. And as someone else noted, .38's tend to be tamely loaded whereas .357 you usually get hot loads anyway because that is what people want and expect.

Some days it's just nice to plink with with a .38 though, all that noise and recoil can get old after a while
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Old May 20, 2013, 09:23 AM   #17
newfrontier45
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Quote:
...there's a few smaller more radical ammo houses still loading some of their hotter stuff to that point - Buffalo Bore, Underwood, probably Grizzly Cartridge and DoubleTap.
No they're not.
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