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Thread: Using the p938 recoil spring in the p380/cw380

  1. #1
    Join Date
    Dec 2018
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    27

    Default Using the p938 recoil spring in the p380/cw380

    I like playing around with recoil springs. To make a long story short, the p938 flat wire recoil springs fit pretty perfectly into the p380. theyre kind of a ***** to get in, and I would never manufacture a gun in this matter, but if you consider yourself skilled at compressing long springs into small spaces (which many of you pm9 owners should be), then I really believe the more consistent force profile of the flat wire recoil spring will increase the reliability of the p380/cw380. The flat wire recoil spring has much more force while the slide is slightly out of battery.
    I have only put 100 or so rounds through it in this configuration so far, so its still a working theory. I will provide updates as I go.. But if any of you have p938 springs and feel like doing some experiments for science... ...


    some minor points: 1) the p938 also has a hammer spring which increases the force needed to compress the slide backward after a shot is fired. The p938 recoil spring on its own is about on par with the p380 dual spring setup (force wise), however it has more force in the 0-1cm out of battery range, which I think will increase the reliability of the handgun.
    2) The spring is a tight fit around the guide rod while fully uncompressed, but still easy-ish to get on. However since the circumference of the spring increases as its compressed, once you get the guide rod into the slide the spring fits great around the guide rod and has plenty of wiggle room to function.


    thoughts? Is this a dumb idea? are flat wire recoil springs better in general?

  2. #2
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    Interesting. That P938 recoil spring is a bear to get back into the 938 too. Keep us posted because I have both and your experiment could prove useful. Thanks.
    The only thing better than having all the guns and ammo you'd ever need would be being able to shoot it all off the back porch.

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  3. #3
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    What’s a p938 and did you measure the strength in lbs of the 938 spring.

  4. #4
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    P938 is a Sig SA 9mm 1911 pocket pistol.
    The only thing better than having all the guns and ammo you'd ever need would be being able to shoot it all off the back porch.

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  5. #5
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    Jun 2014
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    North Carolina
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    I tried, I REALLY tried to get my P938 spring into the P380. Unless my 2 yr old recoil spring is longer then the current one, I don't see how it could be done unless I cut it. I found it to be almost fully compressed when I was about to seat the guide rod. I just couldn't get the front of the rod through the slide. I got it that far by using the 'ol dowel rod through the front of the slide and into the spring to keep everything lined up but just couldn't get it. Then, I struggled getting the spring off the guide rod. It would not slide or pull off. I used a flat blade screw driver to compress the spring end on the guide rod which opened it up enough for me to move it up a speck at a time. It was quite an experience. Anyway, charczard, let us know how things go! Thank you.
    Kahr P380 x2
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  6. #6
    Join Date
    Dec 2018
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    27

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    Quote Originally Posted by topgun1953 View Post
    I tried, I REALLY tried to get my P938 spring into the P380. Unless my 2 yr old recoil spring is longer then the current one, I don't see how it could be done unless I cut it. I found it to be almost fully compressed when I was about to seat the guide rod. I just couldn't get the front of the rod through the slide. I got it that far by using the 'ol dowel rod through the front of the slide and into the spring to keep everything lined up but just couldn't get it. Then, I struggled getting the spring off the guide rod. It would not slide or pull off. I used a flat blade screw driver to compress the spring end on the guide rod which opened it up enough for me to move it up a speck at a time. It was quite an experience. Anyway, charczard, let us know how things go! Thank you.
    sorry I should have been more specific because I actually encountered this at first when trying to get it in. The tip of the front coil has to be towards the bottom left of the hole. That way when you angle the rod into the hole its not blocking the path. when getting the coil off the rod you have to compress and then pull (very much like a chinese finger trap now that i think about it). Yes while the spring is hard to get in and out, once you DO get it in it functions very well. If it were ever so slightly wider in diameter it would be perfect, but this only makes it harder to get in and out, it doesnt affect the function since the springs diameter increases once it gets compressed into position.

  7. #7
    Join Date
    Oct 2020
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    Quote Originally Posted by charczard View Post
    sorry I should have been more specific because I actually encountered this at first when trying to get it in. The tip of the front coil has to be towards the bottom left of the hole. That way when you angle the rod into the hole its not blocking the path. when getting the coil off the rod you have to compress and then pull (very much like a chinese finger trap now that i think about it). Yes while the spring is hard to get in and out, once you DO get it in it functions very well. If it were ever so slightly wider in diameter it would be perfect, but this only makes it harder to get in and out, it doesnt affect the function since the springs diameter increases once it gets compressed into position.
    Hi charczard, thank you for reporting your exciting experiment here. Any new updates?

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