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Converting a Browning Hi Power to .357 Sig

Discussion in 'Handguns: Autoloaders' started by duelist1954, Oct 11, 2011.

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  1. duelist1954

    duelist1954 Member

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    I've got a Browning High Power in .40 S&W. I'm wondering about the feasability of converting it to .357 Sig.

    I'm thinking Re-chambering a 9mm barrel would work...anyone done this?
     
  2. SharpsDressedMan

    SharpsDressedMan member

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    No. It would be easier to just buy a .357 SIG barrel made for the .40 BHP. They are out there.
     
  3. jerkface11

    jerkface11 Member

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    Isn't .357 sig a bit high strung for a hi power?
     
  4. HorseSoldier

    HorseSoldier Member

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    The 40 cal version runs 40S&W fine, don't see why 357 Sig would give it problems.
     
  5. Deaf Smith

    Deaf Smith Member

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    Actually on the stopping power net forum they say a Glock 35, with a .357 Sig barrel, gets 1600 fps from a 125 jhp.

    I bet a .40 High Power would make about 1500 fps or more.

    And yes, no reason a .40 HP can't have a drop in .357 Sig barrel.

    Deaf
     
  6. atblis

    atblis Member

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    Interesting. Barsto sells a 40 to 9mm conversion, but no 357 Sig. In fact, they state "no 357 Sig" twice on the page.

    KKM perhaps?

    http://www.gunandgame.com/forums/powder-keg/1294-40-caliber-hi-power-357-sig.html

    Incidentally, a 40 with light bullets ain't too far off the 357 Sig. How's a 135 gr going 1400 fps sound?

    Want to have a lot of fun? get a Glock 20, and do a 6" barrel with 357 SIG loaded to 10mm OAL (or 9x25 Dillon).
     
    Last edited: Oct 11, 2011
  7. dogtown tom

    dogtown tom Member

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    You would need a aftermarket three lug 9mm bbl.....factory 9mm barrels are two lug.
     
  8. m2steven

    m2steven Member

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    "Incidentally, a 40 with light bullets ain't too far off the 357 Sig. How's a 135 gr going 1400 fps sound?"

    That sounds great. I never thought about that, but effectively you're doing pretty much the same thing. Are the 357 Sig bullets loaded stouter than 40cal ammo you get off the shelf? Are you referring to reloading your own with regards to the light 40 caliber bullets?

    I own a Glock 32 and I guess it's my favorite handgun. I'm a really good shooter with that round for whatever reason. I'd like to hear if anyone has loaded 40 cal brass with lighter 40 cal bullets.
     
  9. ugaarguy

    ugaarguy Moderator Staff Member

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    The cartridges are, yes. SAAMI max average pressure for 40 S&W is 35,000 psi. For .357 Sig it's 40,000 psi.
     
  10. velocette

    velocette Member

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    There might be a reason that Bar-Sto, a VERY reputable custom barrel maker pointedly refuses to make .357 Sig conversion barrels for the Browning .40 BHP.
    40,000 psi blowouts are usually not fun nor pretty.

    Roger
     
  11. Quiet

    Quiet Member

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    bouncing between the 909 & the 702
  12. atblis

    atblis Member

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    35kpsi vs. 40kpsi isn't really that much of a difference. If the Hipower is that marginal that +5kpsi is enough to kill it in short order.... How durable are the 40 S&W Hipowers?

    Everything I see suggests that it's actually feeding issues which is odd because I would think a bottle-necked pistol cartridge would feed better. Dunno.
     
  13. wow6599

    wow6599 Member

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    40,000 psi is really pushing the envelope........and I don't think they make the BHP in 40 S&W any longer, which says a lot. Could be wrong though.
    Besides, a BHP is supposed to be a 9mm.
     
  14. waidmann

    waidmann Member

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    I vote no on two counts. If the gun is not designed for it and the magazine is also not designed for it, pass on it.

    My limited experience is with Glocks and drop-ins. A 22 and a 35 a look in the lower unit and they are not a 31. Slide peening and drag on the barrel convinced me to get a 31 to shoot .357 Sig. The LGS guy says 22 mags work fine. They do until they don't. Okay for the range but..........they are not the same.
     
  15. ugaarguy

    ugaarguy Moderator Staff Member

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    A 14.2% increase in pressure isn't all that much? Okay :rolleyes:
     
  16. HorseSoldier

    HorseSoldier Member

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    I don't think the 40S&W High Powers ever sold super well, nor does the 9mm version compared to tupperware and 1911s. FN Herstal has reduced their support for the design dramatically in the last few years, which I suspect speaks more to market forces than durability issues -- the 40 HPs were one of the few early 40S&W designs that were engineered to handle the cartridge rather than just throwing a new barrel and heavier spring in a 9mm pistol.
     
  17. atblis

    atblis Member

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    It was done out of utter necessity as the initial 40 S&W version service life was extremely short. The 9mm Hipower isn't the most robust design to begin with. They make a big deal out of improvement in the redesign, but that is all presented as relative to the original design. Compared to other 40s, it is still relatively fragile.

    40kpsi is ~ 9mm +P, which is not all that big a deal for most guns.
     
  18. ugaarguy

    ugaarguy Moderator Staff Member

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    9mm +P is 37,500 PSI, the same as 10mm Auto. 40,000 PSI is .357 Maximum pressure. That's serious pressure coming out of a handgun.
     
  19. atblis

    atblis Member

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    Everything I've ever seen indicates that 9mm +P SAAMI pressure is 38.5 kpsi.
     
  20. ugaarguy

    ugaarguy Moderator Staff Member

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    It was early. You're right, it's 38.5k PSI.
     
  21. Pilot

    Pilot Member

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    Atbis wrote:

    I don't think this is true at all, especially for the MK III 9MM Hi Power. The MK III was redesigned with a cast frame, to accomodate the .40 S&W cartridge. It is plenty strong for the .40, and the 9MM. Hi Powers historically have long service lives in sometimes very abusive conditions, even pre MK III.

    Where did you get this information if I may ask?
     
    Last edited: Oct 13, 2011
  22. NG VI

    NG VI Member

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    Saw the same thing when I wanted to get a .357 barrel for my USP .40, and it baffled me then too.


    I don't think it's pressure but momentum and slide velocity that cause the real problems. I mean, the amount of gas pressure is contained by the brass and barrel, all the slide and frame have to deal with is the rearward slide velocity it generates. Is that not accurate? And in that case, .40 and .357 are more alike than not.
     
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