9mm and 40 S&W mags interchangeable

Discussion in 'M, C, L and S Series' started by Barnacle, May 18, 2007.

  1. Barnacle

    Barnacle Guest

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    I heard a rumour that the two calibres share the same mag for A1 models. Any truth to this?
    Thanks,
    B
     
  2. bigtaco

    bigtaco Active Member

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    nope

    bodies are the same size, but the feed lips are different

    you can however, mangle the feedlips and convert a mag. say, to use an s40 mag and get 12 rounds in your s9.

    but the two calibers do not directly interchange
     

  3. Barnacle

    Barnacle Guest

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    Thanks for the reply. I'll steer clear.
     
  4. posterboy7

    posterboy7 New Member

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    I had a brain fart last year and loaded an M&P .40 mag with 9mm. Unfoturnately, I didn't realize my mistake until I had fired a 9mm round out of the gun, was surprised that it went wild, pulled the trigger again and only got a click. When I racked the slide I immediately realize with horror what I had just done.

    The Smith rep told me it was no problem, field stripped the gun, looked down the barrel and declared it undamaged. He said that kind of thing happens all the time. I was so shaken by my mistake that it marked the end of my shooting day.

    I know this is not Glock Talk, but I have to say, I really appreciate that the new Glocks have the caliber stamped on the mag follower and on the top of the chamber. If S&W had done that, the instant I went to thumb that first 9mm round into the mag I would have been reminded of the caliber of gun I was using.
     
  5. Dag

    Dag Guest

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    Interchangeable Mags

    Hi Barnacle

    While 9mm and .40S&W aren't interchangeable, usually, .357Sig and .40S&W are. Most guns of those two calibers only require a barrel swap to change caliber.


    Hi posterboy7

    Since both of those calibers headspace on the case mouth, I'm surprised the 9mm fired at all. It must have been held in place by the extractor. What did the brass look like? Always a good idea to never mix components on the bench. It's just too easy to get a .40S&W mixed into a magazine full of .45ACP, or a 9mm into a .40S&W mag. Anyway, all's well that ends well!

    Dag
     
  6. SELFDEFENSE

    SELFDEFENSE Premium Member

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    To minimize the chance of mix up, I write in Liquid Gold the gun model, the sequential number of that mag in my collection for that gun, and the mag capacity counter-clockwise on the mag base plate.
     
  7. Syntax360

    Syntax360 Premium Member

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    Labeling your magazines is also a good way to keep things straight should one ever be the cause of a malfunction. When my USPc mag springs started failing, I kept forgetting which was good and which was bad by the time I got home from the range - I have a terrible habit of mixing things up when I get ready to leave.
     
  8. Netfotoj

    Netfotoj Premium Member

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    Had one of those "OMG!" experiences with my M357-A1 and M40-A1 shootout, first day I shot the M40-A1.

    Had one FTF with the M40-A1, ejected round, put it back in the magazine, tried again. Click again. Ejected the round and for some reason tossed it in my range bag. Guess I planned to take a closer look at the primer later.

    Figured that was an excellent first outing for the M40-A1, just one FTF. Had one FTF on my first outing with the M357-A1, too, which was most likely caused by racking the slide by hand and closing it too softly. That round I rechambered and fired.

    Anyway, imagine my horror at my stupidity when I was unloading my range bag a few days later and saw the unfired round. Picked it up and saw immediately that it was not a .40 S&W, but a .357 Sig! OMG indeed! If my M40-A1 had fired that round, the results could have been catastrophic. Maybe it wouldn't have hurt anything, but maybe it could have been one of those infamous Glock "Ka-Boom!" incidents.

    Thank God for Steyr engineering that somehow saved me from my own stupidity. Twice! As noted above, .40 S&W and 357 Sig share the same casing and magazines. Only difference is the 357 Sig is necked down to .357 (or thereabouts. According to Wulf, and he should know since he resizes and handloads, it's closer to .355).

    (BTW, I read that when Sig named the round, they purposely left the decimal off the 357 Sig to denote the round wasn't exactly .357. It's actually the same diameter as 9mm, but they didn't want to call it 9mm Sig. They wanted to cash in on the name recognition of .357 Magnum, which the 357 Sig nearly replicates in velocity.)

    Most certainly, one should no more fire a 357 Sig round in a .40 S&W chamber than firing a 9mm in the same.

    No fool like an old fool. I ended up swapping my M40-A1 for a sweet little subcompact S&W 669, so at least I can't make that same foolish mistake again. And my next second Steyr will likely be a S357-A1, I hope soon.
     
  9. brolin_1911a1

    brolin_1911a1 New Member

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    About three years ago, an old shooting friend from out of state came to visit for my son's marriage. Of course Fritz brought his latest guns with him for me to try. Returning the favor in kind, I loaded up some of my more interesting guns in a range back and we headed for the local unmanned outdoor range.

    Well, we shot the .357, shot his .500 S&W, shot my KBI 9mm Hi-Power clone, shot the 1911a1 .45acp, shot some .22LR, more 9mm, more .22, more 9mm. In the middle of all that shooting, since he'd mentioned he'd never fired a Glock or anything in .40 S&W, I got out my Glock 22 and inserted a loaded a mag. He burned through it, said it was nice, and went back to the 9mm. I went to the bench and reloaded the Glock mag to shoot it myself.

    We were shooting at 1 liter pop bottles suspended from string at 50yds. I fired my first shot with the Glock and hit the berm about six feet high. What?!? Must have seriously flinched! Tried again and saw it kick up dirt short of the target. What's going on here. I had to manually cycle the slide both times but was so distracted by the poor shooting that it didn't register. Fired again, and again it was wild. And again I had to manually cycle the action. This time, I looked into the action as it chambered a round and watched the sharply rounded bullet enter the chamber.

    Sharply rounded?!?! My .40S&W loads are all truncated cone! That's a 9mm! I looked at the ground at the goblet shaped brass and immediately realized what had happened. Fortunately, the windage in the bore between the 9mm and the .40 caliber barrel hadn't allowed enough pressure to build up to do more than just expand the case mouths by about a millimeter. That's one seriously rebated rim case!

    I learned two things--one, that 9mm will load and feed from a .40S&W magazine, and two, don't mix the calibers on the shooting bench: shoot one at a time and put the one away before getting out the other.
     
  10. posterboy7

    posterboy7 New Member

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    Yep, that 9mm case was blown out and ripped open on one side. I have it rattling around my desk somewhere.

    The situation was that the local indoor range had several company reps in, S&W, Springfield and Sig. The Smith rep dominated that room. He had worked for Springfield and was damning them with faint praise. He had the most guns out and he was slick. The deal was, you could try any gun you wanted on the range for free all you had to do was pay for ammo. He had the .500 and .460, M&Ps, Walthers, etc..

    I wanted to try out the PPK/S and I did and I liked it a lot. Then I wanted to try one of the XDs and the Smith guy suggested that I also try out the M&P. I asked if he had it in 9mm and he said he only had it in .40 S&W. But I forgot this little fact in between shooting the PPK/S and coming back to the table. I thought to myself, I could split a box of 9mm between the M&P and the XD. So I go shoot the XD, come back and get the M&P. And that is how I made my stupid mistake.

    I just went shooting this afternoon with my wife and her mother. We kept the Smith 3913 9mm in one stall and my G23 and S&W 66 in he other. No way to mix up .40 and .38 Special.

    I numbered all of my Steyr mags, now I have to go and do the same to my Glock mags.
     
  11. xjrat

    xjrat Premium Member

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    My wife and I went to the range a few weeks ago with a friend (who is actually almost in
    police academy, just waiting for the start date) I was shooting my M40-A1
    in one stall and he rented an xd in .45 acp. I was already in the range
    when he came in with the ammo for all of us. I was talking with my wife and
    helping her with HER walther p22, when my friend hands me my ammo
    and he took his to his stall. I was letting my wife shoot first so I wasn't paying to much
    attention to friend because he knows more about guns then I do (he is also a former Marine).
    I glance over and see him picking rounds up off the floor, I go over and ask whats up?
    He said that after loading the mag and inserting into the xd when he went to rack it all
    the rounds just came out of the top of the slide and mag. He said they just fell out all
    over the place. He loaded it again and same thing, He looked at the mag and sure enough
    the top lip of the mag was cracked, %@^!& rental guns. He went and got another mag and
    loaded it up again. I went back to my wife. I saw him fire a round out of the corner of my eye, and
    heard a weird report from the gun. The slide jammed and the empty casing was STUCK in the chamber.
    Friend said that the bullet only went about 10 feet before hitting the GROUND. He just thought it was
    a bad range reload round. when the RO came to look at it and after he pounded the case out he noticed that
    it was .40 s&w not .45acp!!! :oops: The case had blown a huge rip in the side and bulged way out.
    Friend had gotten our ammo mixed up and since I hadn't tried to shoot yet I didn't notice either.
    The RO just loaded the correct size ammo in the xd and shot a few rounds then gave the gun back
    to my friend and he shot 150 rounds through it. The stupid RO didn't field strip or even look down
    the bbl to make sure things were ok!
    I have kept this a secret for my friends sake since he is almost in academy, So this doesn't leave this
    site. :wink: [/i]
     
  12. Dag

    Dag Guest

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    Mistakes with guns

    It's interesting when you think about it. By their very nature, guns are dangerous. Especially when you consider all of the peripheral activities, like reloading, cleaning, loading and unloading magazines, competition, hunting and a bunch of others I haven't thought about. Now consider, relative to the thousands of rounds fired every day, how few serious accidents actually occur. While some of us can tell stories about "stupid" mistakes, how many people do you know that have actually been seriously injured (or killed) when they make such a mistake? Darned few, I'll wager. I would guess that the majority of people injured or killed with firearms were intentionally shot while committing a crime! :!: So as sensible, law abiding gun owners, you should all take a bow! <clapping>

    Dag
     
  13. xjrat

    xjrat Premium Member

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    Very true Dag! when compared to other things
    like people who have a little alcohol and are still sober
    and drive and those who drink too much and drive, it makes
    the amout of rounds fired safely look steller. Guns are
    safe people aren't!
     
  14. posterboy7

    posterboy7 New Member

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    As Massad Ayoob says, people who deal with guns on a regular basis, because of exposure, and inexperienced people, because of inexperience, are the two groups most likely to have an accidental discharge.

    And familiarity breeds contempt.

    I have jumped into training this year, receiving almost 60 hrs of formal training since the beginning of the year and almost all of the instructors and assistant instructors I have learned from have personally witnessed or learned of second hand, incidents of experienced people having serious accidents where they have either shot themselves or other people resulting in injury and death. We don't often hear of them because even instances of serious injury don't get reported in the media.

    Feeding the wrong ammo into a gun is a more minor screw up, but it is the tip of the iceberg and no one can afford to be complacent. Next to not loading the wrong ammo is not picking up live ammo off the ground or floor. One of my instructors says "If it hits the deck it stays on the deck" and he will kick you off of the line if he sees you picking up live ammo for any purpose other than disposal. He saw a highly experienced and respected instructor pick up a .45 round from the ground, load it into his gun and it blew up when he fire it. My instructor didn't say specifically what happened, I think it was too hard for him to repeat, but it may have been death, if not, certainly grave injury.

    Personally, I will not congratulate myself for my safety with firearms until I have forever laid down my guns and have a perfect record and everyone I ever started out in shooting has a perfect record too.

    ...Maybe I should change my handle to "Hijacker", I seem to have a habit of hijacking threads...
     
  15. SELFDEFENSE

    SELFDEFENSE Premium Member

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  16. Thunderbear

    Thunderbear Member

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    That's why you sandbag that mother****er whenever possible. :twisted:
     
  17. Barnacle

    Barnacle Guest

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    Thanks for all the replies, fellas. Shortly before posting my replies I was searching for the member with the avatar pic of the various pistol rounds lined up side by side and wouldn't you know it...he found me! Thanks, Netfotoj! :wink:

    The reason behind my query was that in the Great White North we have to cap our magazines at 10:shock: :cry: . I've heard some of those more clever (or dangerous) than I will feed a 9mm pistol with 40 cal mags so they can carry 11 rounds. If memory serves me correctly, they only differ in overall length by thre hundredths of an inch.

    I've got a 40 so it doesn't matter. For my American cousins who have hi-cap mags I would think it doesn't matter either. Right?
    D :D