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Smith & Wesson M&P question on conversions from M&P 40 to 357 sig or 9mm

Discussion in 'Handgun Discussion' started by EastsideE, Sep 23, 2013.

  1. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    I have a couple of questions that I've been getting mixed results. I have a S&W M&P 40 that i would like to be able to convert to 357 Sig.
    1) I know that Barrel needs to be changed and S&W and Storm Lake have conversion barrels. Are there any other manufacturers? Im more familiar with Glocks.
    2) The mags are interchangeable but does the recoil spring need to be changed?

    Now if I want to change my M&P 40 to a 9mm. I get differing results from gun buddies. Some say they have read that the 9mm conversion barrel can be put in the M&P40 but not the other way around 40 into a 9mm. Others say I would some gunsmith work due to the ramp feed. I really dont want to invest in a 9mm conversion if I cant convert back to a 40 or 357.

    I saw that Storm Lake has a conversion barrel but is it worth it? If so then I would have to buy some 9mm mags then I would have the ability to have 3 calibers with one gun. Thats the goal for right now.

    I tried to do a search for conversions but not specifically for a M&P 40 to 357 Sig or 9mm

    Thanks for your time.
     
  2. strick

    strick McMinnville Oregon Member

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    You can convert from 40 - 9 really easy. Just need a 40-9 conversion barrel from storm lake. Remember the ejection port is bigger for the 40sw over the 9mm, bigger cartridge. If you want 100% reliability you need to replace the extractor and ejector to the 9mm version to function flawlessly.

    I am looking to do this with my Glock 22 myself(the conversion barrel at least). I am not to worried about being 100% reliable. I would only run 9mm out of my G22 at the range for practice. I was thinking about running 357sig from the G22 for edc thou.
     
  3. Nutty4Guns

    Nutty4Guns Portland ADHD Superstar

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    357 Sig just needs the barrel swap. The same recoil spring can be used. I believe EFK makes conversion barrels as well.
     
  4. RicInOR

    RicInOR Washington County Bronze Supporter Bronze Supporter

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    9mm needs it's own magazines. I have tried 9mm in .40 mags - no feeding.
    This was a test due to the un-availability of the 9mm mags recently.


    If you are looking for further clarification, there are a number of discussions, videos, etc over on the offical Smith & Wesson Forums.
     
  5. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Yes that was my concern due to failure to eject - as in this youtube video Update! M&P40 conversion to M&P9 - YouTube
    I think he is using a M&P 9mm not a 40 to 9mm conversion barrel may be part of the issue.
     
  6. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Thats what I figured, didnt know if a stronger spring would reduce recoil or cause failures to eject.

    I was just at the EFK site and they dont have any S&W conversions Smith & Wesson M&P or standard barrels thank though I had EFK target match barrel on my Glock 35.
     
  7. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Thats what I heard you need to replace the barrel and magazines. I didnt know if a different spring is needed.

    I will have to look up the S&W forums still unfamiliar with S&W forums...if you have a link that would help. Ya just want to filter out the crap wanna be sites.
     
  8. Peteralexander78

    Peteralexander78 vancouver Slow is smooth, smooth is fast

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    To got from 40 to 357 you just need a barrel. Cheapest way to go is just getting a stock S&W .357. You dont need the Storm lake or Lone wolf. The stock S&W barrels are about $65-70. To go from a 40 to 9mm you need a barrel and 9mm magazines. You should have no issues with either, but I wouldnt say it will be as reliable as it was. I am in the process doing the same thing. I am just trying to get a 9mm compact barrel, but I have used my full size on my compact and no issues.
     
  9. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Yes Ive seen the stock S&W barrels at midway for the 357 and 9. Just didnt know what happened to this guy that had issues with failure to feed Update! M&P40 conversion to M&P9 - YouTube. Again like many have said not as reliable as it was.

    Good to know that it works for a compact with no issues. I've seen a 9mm compact barrels...if I stumble on to one I'll shoot ya a link.

    Thanks again.
     
  10. XSubSailor

    XSubSailor SW WA Active Member

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    I have an M&P40 and have done both conversions. The S&W 357Sig barrel is cheap and a no-brainer IMO.

    I bought the Storm Lake 9mm conversion barrel and it's a tack driver, but I had numerourous FTEs until I installed the APEX "failure resistant Extractor." It was a pain to change out the extractor due to the extractor pin (lots of info online about this, but I broke 3 punches trying to remove that pin...) I replaced it with a roll pin, and now the pistol performs flawlessly.
     
  11. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Ya too many bubbles in my head LOL I'm Ex Submariner too. Thank you for your service. Ya just wanted to make sure before I commit.

    Good to hear about the APEX fix with the 9mm. Now does is still work flawless with the conversions back 40 or the 357 with the APEX fix installed?
     
  12. XSubSailor

    XSubSailor SW WA Active Member

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    Yes, it works fine in all calibers now.
     
  13. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Just what I need to hear to move forward with this project.

    Thanks for all your help and insight.
     
  14. RicInOR

    RicInOR Washington County Bronze Supporter Bronze Supporter

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  15. RicInOR

    RicInOR Washington County Bronze Supporter Bronze Supporter

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    To follow up on the pin - depending on date of manufacture, you may have a roll pin. If not, recommend to change that out on any M&P.

    And - if you have to pull the rear sight, it was sealed with Red loc-tite , you need heat to loosen the set screw. When you re-assemble use Blue.

    This comes up for certain of the Apex modifications.

    I found that hand polishing was all mine needed and while many people love the Apex kits, a half hour of detail work could save you enough to afford a Seattle coffee.
     
  16. RicInOR

    RicInOR Washington County Bronze Supporter Bronze Supporter

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  17. EastsideE

    EastsideE Eastside Seattle - Newcastle, Wa New Member

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    Thanks Ric for the information and the M&P forum link.

    I got a Email from EFK and they dont make M&P barrels anymore and linked me to GemTech S&W Threaded Barrels - GEMTECH where they only have the 45 and 9mm threaded barrels.
     
  18. datsthat

    datsthat seattle, wa Member

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    I saw a youtube vid about the 40 and 9 barrel having the same exterior so you can simply put a 9 barrel in a 40 (+9 mag)