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why did my M1 carbine keep jamming when i used the 30 round mags?

Discussion in 'Rifle Country' started by rod5591, Feb 18, 2012.

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  1. rod5591

    rod5591 Member

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    I took my .30 m1 carbine to the range. I had 15 round mags and 30 round mags. the 15 round mags worked fine but the 30s kept jamming ever few rounds. Anyone know what might be wrong?
     
  2. rcmodel

    rcmodel Member in memoriam

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    You didn't have real GI surplus 30-round mags, would be my first guess.

    A lot of the after-market carbine mags are crap.

    rc
     
  3. dafitch

    dafitch Member

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    Do you have the correct magazine catch? 30 rd magazines need type 4 catches to work correctly. As for magazines- the 30 rd Korean versions work perfectly for me with the type 4 catch.
     
  4. jeepnik

    jeepnik Member

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    Yep, I'd go with bad magazines. Stick with GI mags and you'll likely not have any problems. Besides, push comes to shove, two 15 round mags that work are far and away better than one 30 that doesn't.
     
  5. USSR

    USSR Member

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    rcmodel is correct; commercially made 30 round mags are crap, use USGI 30 rounders. The mag catch is not likely the problem. I run 30 round mags all the time without a M2 mag catch.

    Don
     
  6. Onmilo

    Onmilo Member

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    I agree with dafitch
    If you don't have the type 4 magazine catch with the offside support tab, the heavier 30 round magazines become mispositioned and rock around a bit which will cause malfunctions.
    Catches are available from Bill Ricca and Orion 7 among other places and are an easy retrofit.
     
  7. Art Eatman

    Art Eatman Administrator Staff Member

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    Sometimes the feed lips aren't righteous, which is easily fixed with some judicious tweaking with needle-nose pliers.
     
  8. rcmodel

    rcmodel Member in memoriam

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    Me too.

    Unless you have an M2 full-auto carbine, the mag catch isn't the problem.

    That's why the type-4 catch came about.

    rc
     
  9. amd6547

    amd6547 Member

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    Plus 1 on the Korean mags...they worked fine in my Inland with the type one catch. I installed a type four catch just for the heck of it.
     
  10. greyling22

    greyling22 Member

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    I was given 4 old 30rd commercial mags. I can't even load them past 12. the follower binds up. do the korean 30's work? I'd like 1 functional 30.
     
  11. briansmithwins

    briansmithwins Member

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    From after action reports I've read, the M1 Carbine was never the most reliable of weapon from the start*. It was rather a rush job and, if i remember 'War Baby' right, they never could make it pass some of the acceptance tests.

    But, since they could be made cheaply by manufacturers that couldn't make M1 Garands, they were massively produced anyway.

    BSW

    *Kinda like the early M16 but w/o the benefit of the additional development work that was done on that rifle.
     
  12. carbine85

    carbine85 Member

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    I agree with this, however I would add the mag catch to your rifle if don't have one.
    The M1 Carbine wasn't really used for it's intended propose. It worked very well for the intended purpose. The problem was it became so popular and in demand that they had to make improvements on the fly.
    The M1 Carbine wasn't known as a jam-o-matic until the M2 kits came along, and the mag catch pretty much cleaned that up.
     
  13. Tommygunn

    Tommygunn Member

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    There are newer Korean 30 rounders that are pretty good mags, but as stated, older commercial ones are .... questionable.
    The M-2 catch with its extra "finger" is a necessity. I found that out on my Inland. Once I put that catch on (an easy as pie fix) my carbine ran fine with 30 rounders.
    Another problem might be magazine lips, or if you use soft nose rounds. Tweaking the mag lips has already been discussed. The carbine was developed to use ball ammo -- what we call FMJ. Some carbines have problems with softnose and hollowpoint rounds.

    I think most of the possibilities have been covered. Giving us a better idea of exactly what was happening, even pictures if possible, always helps.
     
  14. SHR970

    SHR970 Member

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    On my GI 30 carbine I ran into the same problem when running a hollow point load and it didn't matter what 30 round mags I was using. I replaced one part and the problem went away. I replaced the Mag Catch to the M2 style aka type 4. The 30 round magazine came about because of the M2. Change this one part and you should only see issues with the more sloppy of commercial mags.

    What you need
     
  15. Husker_Fan

    Husker_Fan Member

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    The CMP has a great PDF on 30 rounders. Mine are all AYP stamped. These were made by FN for NATO contracts after the war. They work flawlessly and are the only non-GI mags of older vintage that do. The currently available mags from Korea are also very good.

    As for the catch, I run a type 3 with 30 rounders. I think the added support of the type 4 is good if you are putting a lot of torque on the magazine by banging it around in the jungles of SE Asia. Otherwise, for run of the mill range and HD duty, I don't think it's necessary.
     
  16. Husker_Fan

    Husker_Fan Member

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    That's interesting. I have some HP bullets that I have not loaded up yet. I'll be interested to see how they work, and if they don't, I'll get a new catch. The SPs I've used work fine, but they all have a profile nearly identical to the FMJ.
     
  17. bigfatdave

    bigfatdave Member

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    Perhaps it would help to know what version of the M1 carbine the OP has ... and what ammo/magazine is being used

    Based on this thread I'm taking everything with a grain of salt, rod5591 appears to be very new to maintenance and troubleshooting on firearms.

    And "jamming" doesn't begin to describe the malfunctions, were the rounds going nose-up or nose-down while feeding? Was it just not quite making it back to battery? Is there some other underlying problem? Is the magazine garbage? (I've been burned by crap magazines, it happens and you move on) Is the ammo underpowered? Is the gas system in good repair and clean? Is the carbine a CMP rebuild, a good commercial model, a bad commercial model, or a war relic?
     
  18. 1KPerDay

    1KPerDay Member

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    The Korean 30 rounders have been flawless for me with and without the M2 mag catch. More reliable than my GI 15 rounders, actually.
     
  19. ball3006

    ball3006 Member

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    You answered your own question with your post. It is the magazine. If your rifle operates just fine with 15 round mags, why fool around with 30 round mags that don't work? chris3
     
  20. zeke

    zeke Member

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    "The M-2 catch with its extra "finger" is a necessity. I found that out on my Inland. Once I put that catch on (an easy as pie fix) my carbine ran fine with 30 rounders."

    ditto, and the 30 round Koreans are close to the old military versions.
     
  21. mortablunt

    mortablunt Member

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    They are blam aftermarket commercial mags. Aftermarket mags for old military surplus guns tend to be junk.
     
  22. Nicky Santoro

    Nicky Santoro Member

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    OP,
    Even the old genuine USGI 30 round mags were never as reliable as the 15s. Unless your 30s are true USGI or even Korean you'll likely find them problematical.
     
  23. Art Eatman

    Art Eatman Administrator Staff Member

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    In the way back when, I'd occasionally liberate a 600-round can of ammo and go down to the beach at Inchon and harass seagulls with my M2. All we had were the 30-round mags. Everything always worked.

    My father's bring-back M1 works okay, 15s or 30s.
     
  24. rod5591

    rod5591 Member

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    the jams were nose up. the ammo was Remington 110 gr UMC. the mags were made in USA. see pics. I dont know what catch it has. I took some pics. I have a 1944 Underwood.
     

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  25. briansmithwins

    briansmithwins Member

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    Not to sound like a D bag, but that carbine might work better if you clean the old, dried out cosmoline off of it.

    BSW
     
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