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Can you shoot 9mm out of a .357 Sig?

Discussion in 'Handguns: Autoloaders' started by natedog, Oct 5, 2003.

  1. natedog

    natedog Well-Known Member

    Well, can you?
  2. Dan Shapiro

    Dan Shapiro Well-Known Member

    Yes, if there is a conversion barrel made for the handgun in question. I have a BarSto 9mm barrel for my SIG Pro.
  3. Hypnogator

    Hypnogator Well-Known Member

    Sure, if you don't mind ruptured cases and major gas escapes!:evil:
  4. Pheonix

    Pheonix Well-Known Member

    How will the pin hit the primer?:scrutiny:
  5. Quartus

    Quartus Well-Known Member

    Occasionally, would be my guess. :D
  6. 10-Ring

    10-Ring Well-Known Member

    I guess you could, but it would be fun.
  7. Ant Mod

    Ant Mod member

    Think about what the .357 sig cartridge is. Its a 9mm shell necked down to a .357. If it necks "down," as in gets smaller, do you think the 9mm round will fit or travel down the barrel?
  8. Rich357

    Rich357 Well-Known Member

    I've seen it happen twice. The 9mm case was badly bulged. It didn't rupture. The case didn't clear the ejection port. The bullet hit close to the point of aim each time.

  9. BluesBear

    BluesBear member

    9mm is .355.

    .357 is... well... er... um... it's .357.

    Wouldn't that be necked UP?

    (Sounds like something Gaston would try.) :evil:
  10. stans

    stans Well-Known Member

    Actually, the 357 Sig is a 40 S&W case that has been necked down to .357. The 9mm case rim is smaller in diameter than the 40, so the case is not going to fit the breechface correctly. You probably could fire a 9mm round in a 357 Sig pistol, but the case will either be severly bulged or ruptured and accuracy is likely to be poor.

    A pistol chambered in 357 Sig can likely be converted to fire 9mm by replacing the barrel, slide, recoil spring and possibly the magazine.

    A pistol chambered in 357 Sig can be converted to 40 S&W by changing the barrel and perhaps the recoil spring and magazine.
  11. mr. e

    mr. e Well-Known Member

    I have heard about, but not seen, a 9mm conversion barrel for the SIG P229 40 Auto model. It already has a drop-in 357 SIG barrel. From what I remember, there are only two complications. One is the mag, which would have to be modified to hold the 9mm rounds correctly. The other is the extractor, which I guess would have to be replaced with one that would extend deeper to grab the rim of the cartridge.

    It sounds way to complicated and not worth the effort.

    By the way, I read that the 357 SIG bullet diameter is the same as the 9mm (.355, or is it .354?) not .357. It was named the 357 SIG because Sig-Sauer was looking for the same velocity as the 125 gr. .357 Magnum round in an autoloader and they thought it would be a good marketing name. (What's a few thousands of an inch among friends?)

    I have loaded the 357 SIG with 9mm bullets, but most brands are not shaped so that the casing can get a grip on them when they are seated properly. The 357 SIG bullets have longer shoulders, but they are the same diameter as the 9mm.

    Here's a link for a lot of good 357 SIG info:
  12. caz223

    caz223 Well-Known Member

    99.999% of all commercial loads available now for the 357SIG are actually .355, same size as 9mm.
    And Lunde organized a group purchase of 9mm Bar-sto barrels for the SigPro 2340.
    I was a happy recipient of one for the mere cost of $166, shipping and all.
    9mm ammo loads and feeds fine in the stock mags, and operates the slide just fine.
    12 fit in the stock 10 round magazine, and they load easily.
    They feed and extract 100%, and why not, my dillon 550 uses the same shell plate for .40, 9mm, and 357SIG.
    I would imagine that 9mm would shoot fine through the 357SIG barrel, but the brass would prolly be too stressed to do that repeatedly, and you already have the gun, why not buy the right ammo, or get a conversion barrel?
    I would imagine that the brass case wouldn't seal well, and would fail to cycle, but 1 bullet would be in the air, and you would prolly have to fumble around, clearing various jams.
    I still wouldn't do it except as a last resort.
  13. Walt Sherrill

    Walt Sherrill Well-Known Member

    Several years back when I was a regular reader (and sometime participant) on the SIG Forum, shooters there had Bar-Sto conversion barrels that did this beautifully. Bar-Sto does its magic in the conversions so that extractors are OK, and headspace is correct. It can be done.

    One gun with three barrels... 9mm, .357 SIG and .40 S&W.

    You might need different mags, but that's not a certainty. In most cases, the mags worked too (as is often the case with .40 or .357 SIG mags in a 9mm pistol.)
  14. PCRCCW

    PCRCCW Well-Known Member

    Like previously stated the 357 Sig is a .355" bullet. Or a 9mm stuffed into what is basically a necked down 40 case.

    They called it the 357 Sig, because the entire theory behind the bullet was to duplicate a 357 Mag's ballistics in a s/auto gun.

    They are just playing off of the MAG's name and well established rep.

    Man, misleading information for the sake of marketing...can you believe it?

    :D :rolleyes:

    Shoot well...............
  15. care-less

    care-less member

    sounds like a whole lot of people don't know the difference between a 9mm, and a 357sig.
  16. Ant Mod

    Ant Mod member

    Ah my fault. For some reason I was thinking it was the 9 case necked down.
  17. Al Thompson

    Al Thompson Moderator Staff Member

    No biggie Ant. We're just happy to see you here! Welcome! :)
  18. Al Norris

    Al Norris Well-Known Member

    BTT, because I need some related info.

    I'm thinking of getting my son a neat xmas present when he comes home on leave (USMC - Camp LeJune). He has a Sig P229 in 357sig. He has mentioned that he would like a .40 barrell. Is that all I need to get him? Springs? Anything else? I think I remember reading somewhere that the slide and mags were the same for the .40 as the 357sig.

    Any help would be appreciated.
  19. mr. e

    mr. e Well-Known Member

    Everything is the same on the P229 for either the 357 SIG or 40 auto cartridge. Only the barrel needs to be changed.
  20. Al Norris

    Al Norris Well-Known Member

    Thanks. I was hoping it was that simple.

    I pick my son up at the SLC airport on the 23rd. He's bringing all his guns home, as his unit will deploy back to Iraq after the new year. I thought this would be a nice send off, as he will be able to take the sig with him, if it's in .40s&w.

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