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9mm versus .357 Mag - Ballistics ???

Discussion in 'Handguns: General Discussion' started by TheMrBillShow, Nov 20, 2011.

  1. TheMrBillShow

    TheMrBillShow New Member

    Dec 16, 2008
    Suburb of Milwaukee, WI

    I am very much into ballistics, and all of the physics therein...

    But I have a question that seems to have no easy answer...

    The 9mm x 19 Luger Cartridge has a max standard SAAMI pressure of 35,000 and is popular with a 124 grain bullet...

    The .357 Magnum also has a max standard SAAMI pressure of 35,000 and is popular with a 125 grain bullet...

    Yet the factory ammo's muzzle velocities and energies are considerably different...

    In general the .357 Magnum 125g has velocities of about 1300-1700fps developing energy of about 500-800fp...

    The 9mm 124g has velocities of about 1000-1200fps developing energies of about 300-400fp...

    Handy data at: http://www.ballistics101.com/

    This is a 66-100% difference in energy... One could say the .357 cartridge in standard factory loadings is up to TWICE as powerful as the 9mm...

    Yet both are launching a same diameter and weight bullet, at the same SAAMI preasures...

    Is there an explaination...??? :confused:
  2. kozak6

    kozak6 Active Member

    Apr 10, 2011
    If I had to guess, the .357 probably provides a larger volume of gas.
  3. 1KPerDay

    1KPerDay Elder

    Jan 19, 2006
    Happy Valley, UT
    Same pressure, but for a longer duration. That's a guess.
  4. BeerSleeper

    BeerSleeper Active Member

    Mar 24, 2010
    case volume. a 357 mag case holds slower burning powder, and more of it.

    Also, a 4 inch revolver barrel is longer than a 4 inch semi-auto barrel. The semi auto barrel measurment includes the chamber, the revolver measurement starts at the end of the cylinder. In short, the pressure on the 9mm (which started out with less powder, and less chamber volume) falls off faster as the bullet moves down the bore.
  5. wanderinwalker

    wanderinwalker Participating Member

    Jan 6, 2003
    SW NH
    Ballistics are like engines: you can get similar amounts of power out of something smaller by running it at higher pressures, but at the end of the day there is no replacement for displacement.

    The 9mm Luger is like a turbo 4. At 35k PSI, it's a pretty efficient little round, you can toss a 115gr bullet at about 1150-1200 fps with little trouble. But at those speeds and bullet weights a .357 isn't being used at its best. You can toss a 158gr .357" bullet out of a 4" .357 revolver at about 1200 fps, which is a pretty considerable power boost. The 9mm simply lacks the capacity to do that.

    For reference: most of my 9mm reloads run on 5-6gr of powder, depending on exact bullet weight and powder used. My .357 at magnum loadings burns between 14-20gr of slower powder, giving more gas volume and bullet speed.

    Power really has nothing to do with operating pressure and everything to do with how much powder you can burn and how heavy of a bullet you can throw.
  6. tipoc

    tipoc Senior Member

    Mar 9, 2006
    It's useful to pick up a few reloading manuals when you can, Speer, Lee, Sierra and/or others and look at the information available there. As wanderingwalker said, operating pressures are only one part of it.

    Do some figuring...why is the .357 more powerful than the .38 Spl.? Why is the 10mm more powerful than the 40S&W? Why is the 38 Super, with a lower operating pressure than the 9mm, a more powerful round than the 9mm?

    Interesting exercises.

  7. RatDrall

    RatDrall Active Member

    Apr 12, 2009
    Very few loads go above 1400 fps.

    My Glock 17 fires Federal 9bple +p+ closer to 1400 fps.

    The fastest 9mm loads are closer to the average .357, as far as velocity. I'd guess the .357 is more devestating because it is open to any bullet design concievable, due to it never having to feed smoothly into a chamber like a semi-auto round does.
  8. TheMrBillShow

    TheMrBillShow New Member

    Dec 16, 2008
    Suburb of Milwaukee, WI
    Ballistics 101 Shows 32 off-the-shelf factory 357 Mag rounds at 1400fps or over...
    (doesn't seem like "very few" to me...)

    9mm has to go to at least +P, with very light bullets, to get over 1400fps...
  9. cougar1717

    cougar1717 Active Member

    Nov 19, 2007
    St. Louis, MO
    This site is very helpful in seeing the correlation between powder capacity and velocity: http://data.hodgdon.com/cartridge_load.asp
    There can be some exceptions, but more powder usually translates to more velocity, especially in when comparing these two cartridges. Even just looking at the cartridges should give some clue as to their relative power. The 357 mag measures 1.590" while the 9mm is 1.125". That's almost a 1/2" taller.
  10. CDW4ME

    CDW4ME Active Member

    Mar 15, 2009
    My chronographed velocities (average for 5 shots):
    Glock 26 / Winchester Ranger T 124 +P @ 1,162 fps = 372# KE
    Glock 26 / Winchester Ranger T 127 +P+ @ 1,182 fps = 394# KE

    Glock 19 / Winchester Ranger T 124 +P @ 1,212 fps = 405# KE
    Glock 19 / Winchester Ranger T 127 +P+ @ 1,238 fps = 433# KE

    Kahr P9 / Federal 115 gr. +P+ 1,272 fps / 413# KE.

    I no longer have any of these revolvers, but here is what I got with them:

    Ruger Speed Six .357 Mag (2 3/4'' barrel)/ Federal 125 JHP @ 1,248 fps / 432# KE.

    SP101 / Winchester 110gr. JHP @ 1,208 fps / 356# KE.

    Taurus 617 (ported) / Federal 125 gr. .357 magnum JHP @ 1,143 fps / 363# KE.

    With typical SD ammunition and typical CC guns the hottest 9mm loads compare favorably with 357 mag.
  11. NM Mountainman

    NM Mountainman New Member

    May 12, 2008
    New Mexico
    There are many variables involved.

    There are many variables involved. Some of them have been mentioned in previous posts. The case capacity, amount of powder, and amount of gas produced are among the biggies.

    Another consideration is barrel length. A typical 9mm pistol has a 4" barrel, which provides less than 3" of rifled barrel for the bullet to accelerate in. A typical .357 revolver has 4" or greater length barrel (plus 1.6 inches of chamber length.)
  12. chris in va

    chris in va Mentor

    Mar 4, 2005
    Louisville KY
    9mm is designed to be fired out of a pistol barrel, and has faster powder. 357 gains a lot of velocity when shot out of a rifle barrel with it's slower powder.

    You may get an extra 150-200fps out of a 9mm carbine, but put a 357 in the same length and it'll reach 1700fps without too much effort.
  13. rcmodel

    rcmodel Member in memoriam

    Sep 17, 2007
    Eastern KS
    It's all about case capacity and how much of which burn rate powder each will hold.

    The 9mm is a small case, so faster burning powder must be used in smaller charges.

    The .357 case can hold two to three as much slower burning powder.

    Typical loads 124 - 125 grain loads:
    9mm = 5.8 grains Alliant Unique powder.
    .357 = 17.5 grains Alliant 2400 powder.

    Or put another way.
    Hit a bowling ball with a clenched fist as hard as you can = 9mm.
    Push a bowling ball with the palm of your hand using the same pressure = .357 Mag.

  14. BlindJustice

    BlindJustice Senior Member

    Jul 26, 2007
    Pullman, WA
    rcmodel nails it

    but you could also keep in mind the slower burning powder in the
    .357 Magnum produces those higher velocities via 6" or longer barrels
    .357 Mag - the shorter the barrel the more significant velocity losses are
    because of unburnt powder blowing out the muzzle on 4" 3" 2" Bbl..s

    (mm platform - many carry more than twice the number of rounds
    than a .357 Mag so something of empty the gun and what's the total
    ft lbs delivered in each case eh?


  15. wanderinwalker

    wanderinwalker Participating Member

    Jan 6, 2003
    SW NH
    Well, yes and no. Yes, slower burning powder is better consumed with more barrel length. But no, burning more, slower powder still gives you more speed than smaller amounts of faster powder, even in short barrels.

    With a 4" .357 it isn't any trick to hit 1200-fps with a 158gr bullet. Nothing in a 9mm will reach that. Even a 2.5" revolver should get close to 1100-fps with that same 158 gr load.

    I don't have longer or shorter revolvers to chronograph .357 ammo through, just a 4" S&W, but I do have a Glock 26 and a 17 for 9mm. I just checked my notes: two different reloads go 60-fps faster in the 17 vs the 26 (1" of barrel difference). I would expect a 2.5" .357 to post numbers more in the 100-fps slower than a 4" gun, depending on the ammo.

    (For the record, I am a long-time member of the "nine is fine" camp, but also believe nothing in a semi-auto can match the sheer horsepower capability of a Magnum revolver round. Even the 10mm... :p )
    Last edited: Nov 23, 2011
  16. jmr40

    jmr40 Mentor

    May 26, 2007
    You have published velocities and real velocities. Most 357 mag velocities you see published are from 8" test barrels. When you fire those loads over a chronograph with 4" barrels and with cylinder gaps to contend with the velocities are MUCH lower. Most published 9mm velocities are much closer to what you will actually get.

    If you are comparing real world velocities of 124/125 gr bullets fired from 4" 357 mag revolvers and 4.5" 9mm pistols you will find the 357 has very, very little advantage. Go below 4" on a revolver and the 9mm will be shooting faster in many cases.

    After buying a chronograph I stopped using 357 guns for SD. When used with heavier bullets in longer barrels they have their place, but I couldn't see using a 6 shot gun with excessive recoil and muzzle blast to gain almost no advantage over a 9mm.
  17. easyg

    easyg Senior Member

    May 19, 2007
    off-line mostly.
    Not true.

    Even from a 4" barrel the .357 magnum will deliver about 150 additional ft. lbs. of energy than even the hottest 9mm ammo.
    And that is significant.

    Very few 9mm+P+ rounds will even come close to delivering 500 ft. lbs. of energy.
    .357 magnum rounds routinely deliver well over 500 ft. lbs. of energy, even from a 4" barrel.

    This is one of the reasons the 357Sig was created....to get that 125g .357 magnum performance from an autoloader.
    Something the 9mm just can't achieve.
  18. Dr.Rob

    Dr.Rob Moderator Staff Member

    Dec 23, 2002
    Centennial, CO
    I noted a 125 gr Remington soft point fired out of a 2 inch Colt Magnum Carry was going through the chronograph at about the same speed as a 4 inch 9mm FEG Hi-Power was shooting 115gr silvertips.

    The 357 still 'sounds' more impressive.. more bark more muzzle blast--and that could be a factor if you were facing it.

    But when you get into 4 and 6 inch barels the 357 leaves the 9mm in the dust.
  19. Strykervet

    Strykervet member

    Nov 16, 2010
    Those first few posts just about nailed it. Notice Corbon's 110gr. JHP in .357. 1350fps from a 4" barrel. Their 115gr. JHP in 9mm+P is 1300fps from a Glock 17. They are almost identical when you factor in difference in bullet weight and therefore it wouldn't surprise me if the load was almost identical, ie, a fast burning powder.

    Looking at my loading data for Viht in Loadbooks, .357 mag fired from a 7" bbl., the data for the 3N37 powder, a popular 9mm powder and my favorite 9mm powder and fast burner (very clean, low flash) is 1646fps for a 110gr. bullet at 35,000psi, and seems to be near equal to 9mm data for the same bullet weight given the barrel length (consider also I get 1500fps from a G17L with 115gr. +P and +P+, and 1600 with 110gr. from a 6" 686+). But things change when you move to the slower burning N110. The data from a 7" bbl, max load 110gr. XTP is 1909fps! That would still be smoking with a 4" bbl.

    The 145gr. lead bullet goes 1368fps max using 3N37, so about 1000 or so in a 4" and same with the 147gr. 9mm in a G17. But with the N110, 1591fps.

    The 125gr. XTP goes 1772fps max using N110, and I've clocked 1700fps from a 6" 686+. No 3N37 data.

    Problem lies in that the slower burning powders, the N110 for example, use 18.4 grains for the 125gr. XTP! 5.56 uses about 20gr. of powder and it almost fills the case, keep that volume in mind, so the slower burning powders in the .357 simply fill the case up, and the 9mm case just isn't that big. It might accomodate 10gr. IF you compressed it, but that just isn't enough. The slower burning powders, they often don't burn all the way and have a huge muzzle flash, and may (the following is my opinion) not be able to generate the proper force necessary to operate a traditional size slide on an auto, with the DE being the exception but it is gas operated and not traditional sized. And I'd think you'd need a fixed barrel.

    This about sums it up. Ultimately has to do with case capacity and slower burning powders. It would also be interesting to note that the .357 using 3N37 uses a few extra grains vs. 9mm to obtain similar velocities due to the fact it leaks between the barrel and cylinder.
  20. MachIVshooter

    MachIVshooter Elder

    Aug 11, 2005
    Elbert County, CO

    Pick up a copy of "cartridges of the world". It covers virtually every metallic and shotshell cartridge ever manufactured (or wildcatted with some notariety). It gives a brief history on their development, a short list of common uses and some other details.

    Looking at the different cartridges with the same bore diameter but wildly varying case capacities and operating pressures, and you will understand that bore size has very little to do with power.

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