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.357 SIG Reloading Myths

Discussion in 'General Glocking' started by Mike6158, Mar 13, 2010.

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  1. Mike6158

    Mike6158 Random Grouper

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    Myth #1: Most of the time when someone "describes" the .357 SIG cartridge they call it a necked down .40 cal case. It's not. The Sierra reloading manual explains the difference... basically the .40 case is too short once you neck it down (.020 too short) and the .357 SIG head spaces on the case mouth. A cartridge that is too short would be a problem. 10mm cases are long enough (too long actually) but they use a large pistol primer vs the small pistol primer that the .40 uses so they aren't a good candidate.

    Myth #2: Any 9mm pistol bullet will work for reloading the .357 SIG. This is a big time no. Most 9mm bullets are too short. Round nosed bullets, that I've found anyway, won't work. There are some flat nosed bullets that will work. Sierra only makes 4 bullets for the .357 SIG. Conversely, btw, bullets for the .357 SIG will work on a 9mm. I've loaded 9mm RN bullets in .357 SIG cases but (A) not many and (B) none were fired. Bullet setback is a huge problem due to COL requiring that the bullet be seated into the ogive which gives you less or even no neck tension

    So what really prompted this post? Well... somehow a .40 case found it's way into the case feed bin on my Dillon XL650 the other night. I was loading .357 SIG. I was using brand new Starline brass and 125 grain Sierra bullets. How the .40 case got in there I don't know but I found it today while shooting. About 6 rounds into shooting the weapon would not fire and the slide wasn't closed all the way. I tried to cycle the weapon and the slide would not move. Eventually I tugged on it hard enough and the round was dislodged. Still not understanding what had happened I tried to chamber the round again with the same result. After the second time I set the round aside and finished shooting what was left in the magazine with no other problems. Later I looked closely at the round and the first thing I noticed was that it was stamped .40. I've included a picture of the round... Can you see the other difference (which is why it would not chamber) :wow:

    [​IMG]
     
  2. eforney

    eforney

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    Not resized all the way down?
     

  3. threefeathers

    threefeathers Scouts Out

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    I've loaded 2K of these for 4 handguns.
    Once you have it down it is easy.
    1. Use 357 Sig brass.
    2. Use maximum powdercharge as there is really not a lot of play here anyway. You want the case filled which will assist in stopping a bullet drifting into the case with recoil.
    3. Taper crimp, period.
    4. Use 357 Sig or 38 Super bullets.
    I get Montana Gold and Speer 357 Sig by the K.
    I use either 800X or Unique powder, both work really well.
     
  4. Mike6158

    Mike6158 Random Grouper

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    No- A .40 case made it into the case feed hopper. .40 is a straight walled case. .357 is a necked down case. My .357 die created the neck on the case during resizing but it also caused the bulge at the bottom. I assume that came from the resizing operation and the added force on the case.
     
  5. AustinTx

    AustinTx

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    The case walls are thinner on the 40S&W than the 357sig brass. That's what I've been told. The SAAMI pressures are higher for the 357.
     
  6. LoadedTech

    LoadedTech

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    I was going to say the .40 case was resized to .357 sig when it reached the case webing which couldnt be resized. Thus, causing it to not be chambered properly because it hit the ,40 web and wouldnt allow the slide to reach lock. But, thats what I see. When I reload .40, there is a band around the bottom of my cases, not an indent, like shown.
     
  7. Mike6158

    Mike6158 Random Grouper

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    I don't know how many I've loaded. Thousands... on the Dillon that's only about 3 hours of loading time though :supergrin:

    (1) I do... somehow a .40 case ended up in the feeder.
    (2) I would be careful about saying that on the internet. I know that you mean the max charge listed for a specific powder in the load manual but that could easily be mistaken to mean fill the case with whatever powder. Not a good idea for RE17, etc.

    Unique, Zip, HS-6, AA #7, Viht 3N37... all good powders. Zip is just a tad faster burning than Unique and a max charge (for 125 Gr JHP) of Viht 3N37 is .8 grains (7.7 vs 8.5) more than Unique plus it gives (book value) 1,300 fps vs 1,250 for Unique. AA#7 is an even better case filler at 10.5 grains for a full charge and 1,300 fps vs 1,250 fps for Unique.

    (3) No choice there IMHO...

    (4) As long as the straight portion of the bullet is long enough for good neck tension and a good crimp while still meeting COL the bullet should work. So far I haven't found a round nosed bullet that will work. Flat nosed... or JHP but not a lot of choices. Speer, as you noted, has good bullets. Sierra has 4... Rainier makes a good flat nosed bullet...
     
    Last edited: Mar 14, 2010
  8. threefeathers

    threefeathers Scouts Out

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    You are correct, maximum charge of the correct powder.
    I actually got the best velocity out of 800X but good old Unique still putts along.:wavey:
     
  9. viniglock

    viniglock

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  10. Mike6158

    Mike6158 Random Grouper

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    Here's a shot of the right brass vs the wrong brass loaded with the same bullet. The .40 case is noticeably shorter with a pronounced bulge at the base of the case

    [​IMG]
     
  11. Brian Lee

    Brian Lee Drop those nuts

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    True post.

    It's widely publicized that the .357 brass is not made from .40 cases, because as the OP points out, they're about .020 too short. But to say that a .357 Sig is a necked down .40 is still a good way to explain to people unfamiliar with the cartridge what the basic idea behind it really is. The outer dimensions are the same at the back end, and aside from wall thickness, and the extra length required to make the step in the neck, the .357 Sig really was an idea that started with a guy saying "hey lets neck down the .40 to accept 9MM bullets." And likewise, the 9x25 Dillon started with a few guys making the same suggestion about necking down the 10MM. But it goes without saying at this point, that some other small details made it all a bit more complicated than that.

    Anyone who was actually setting up to reload .357 Sig would probably have no trouble finding out that you cannot make your own brass out of spent .40 shells. But as I understand it, you can make your own 9x25 brass out of spent 10MM cases. I suspect the 9x25's overall length was chosen so as to make this possible, since it was expected that the cartridge would likely always remain a wildcat, and reloaders would have little choice but to run old 10MM cases into a 9x25 die.
     
  12. G20gunner

    G20gunner

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    The 40S&W is loaded to a max pressure of 35,000psi, the 357SIG is loaded to a max pressure of 40,000psi. That's a pretty big jump:shocked:.

    G20gunner:wavey:
     
  13. Steel Head

    Steel Head Tactical Cat

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    Introducing the GLOCK 357 BELTED MAGNUM:tongueout:
    [​IMG]
     
  14. Mike6158

    Mike6158 Random Grouper

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    :rofl:

    Now if I could just get some royalties
     
  15. English

    English

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    Many people have necked down .40S&W cases to 357SIG without problems. For maximum loads the case strength might be a worry but the slight reduction on overall length is not very significant. In spite of what so many manuals say, the 357SIG should head space on the shoulder and not on the mouth. The step that the mouth is supposed to sit on is cut to far forward in most chambers. This results in inconsistent ignition and reduced accuracy. Obviously, it cannot head space on both at the same time and the solution is to use the shoulder. This also reduces the working of the case and makes the cases last longer.

    The shortening of the case is more important for crimping the bullet. As the OP says, 9mm bullets where the crimp is on part of the ogive will produce setback. The 0.02" shorter case means that the neck is reduced in length from 0.11 to 0.09". Nearly 20% less!

    It is difficult to get enough (actually impossible) pressure to crimp the case to the bullet strongly enough for consistent accurate performance without crushing the case walls downwards with conventional taper crimping dies. The shorter neck of the necked down .40S&Ws make this even worse. Lee have a complete solution to this with their collet type crimper, the Lee Factory Crimp Die. Even with necked down .40S&W, this should give enough crimp strength.

    The above is not my work but that of the editor of Real Guns. If you start with www.realguns.com/archives/112.htm and follow his links to earlier articles, it should tell you all you need to know about reloading 357SIG relative to set back and die adjustment.

    English
     
    Last edited: Mar 14, 2010
  16. Hydraulicman

    Hydraulicman

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    if both cartridges went into teh same die. why are the shoulders and bullets at different hights?
     
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