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Thread: M11A1 Large Magwell Slowfire .380 with CF-W A Bolt and Z-mags

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    M11A1 Large Magwell Slowfire .380 with CF-W A Bolt and Z-mags

    Well, I thought some of you might be interested to know that I've had some luck getting slowfire .380 to work with my large magwell M11A1, Z-mags, Baby Ghost upper and V2 CF-W A bolt. I still have more testing to do but the initial results are promising:

    https://www.youtube.com/watch?v=Bu0Y7Bgmv-o

    On to the details...
    The gun was suppressed with a Thompson Machine SG-2. I believe running suppressed is the key to getting this to work. I don't think it would be possible without the can based on Strobro32's testing.
    Ammo was MaxxTech .380 95 grain. I believe it's also important to have ammo that runs a little hot.
    The spring I used was painted orange on one side, and I cut it to about 77 coils. (reference this post for previous testing done by strobro: http://www.uzitalk.com/forums/showth...l=1#post798440)

    Earlier testing that I did with PAM-2 380 mags and a spring at 70 coils was very unreliable. However during that test I had a Z-mag with me that actually ran pretty well, so I decided to try again using Z-mags with a few more coils in the spring to see if increased bolt speed would help with feeding reliability.

    For my testing, I brought 4 Z-mags to the range. I started with ~5 round burst fire to make sure the gun would not run away with the stronger recoil spring. Of the 4 mags using burst fire, two failed to feed about every 5-10 rounds. However, the other 2 Z-mags functioned flawlessly. Based on that, I reloaded the 'good' mags and then dumped each one. Both dumped with no issue, one of those is the subject of the video linked above.

    So, I have about 120 rounds down range with the two good Z-mags and 0 failures. Obviously, more testing is required but I'll say this is a pretty promising result. I have 2 more 30 round Z-mags, and some 50 round Z-mags to test as well. I also plan to run my two good mags again just to verify that the initial results are repeatable.

    For now though, I'll leave with this - slowfire .380 is a blast! It's completely flat with almost no recoil, quiet and exceptionally controllable...

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    I got 799 RPM from the video.

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    Quote Originally Posted by strobro32 View Post
    I got 799 RPM from the video.
    That's a nice cyclic rate.

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    Had some time recently to pick this back up, and I'm now calling 100% success.

    After my initial post I was having some issues with extraction. It looked like the brass was occasionally dropping out of the extractor and then getting left in the chamber to spoil the fun for the next round. So I pulled out the extractors from the CF-W A bolt and the OEM 380 bolt. When I put them side by side, there are subtle differences between the 380 extractor and the 9mm extractor that came in the A bolt. Namely, it looked like the distance from the centerline of the pin pivot to the extractor 'claw' was a few thousandths longer (maybe 5-10? didn't measure...) on the 9mm extractor. I suspect this is why the 9mm extractor was dropping the 380 brass in the chamber.

    So I installed the 380 extractor in the A bolt. Of note, the metal around the pivot pin was much thicker on the OEM 380 extractor, so it had to be filed down to be installed in the A bolt. Now this thing really does run flawlessly. Here's a quick vid of a friend of mine behind the trigger:

    https://www.youtube.com/watch?v=bIlEyNxR_tI

    So the keys to success here are finding which of your Zmags will run 380 (about half of mine won't, and I can't tell why), getting the right extractor in the A bolt and shooting suppressed. From there it's just a matter of tuning the spring.

    One question that I have now - anyone know where I can get more OEM spec 380 extractors? Most everyone seems to be selling 1 extractor for both 9mm and 380...

    *Edit*
    Ok, I see that FTF lists separate 380 extractors. Anyone have experience with these?
    Last edited by tlk; 09-26-2020 at 12:06 PM.

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    Does the 380 extractor work with 9mm?

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    Went ahead and bought a 380 extractor from FTF, which just arrived. From what I can recall it looks identical to the one that I pulled out of my OEM 380 bolt.

    This time I put it side by side with the 9mm extractor from the CF-W A bolt and took a couple pictures, one close up and one with my best attempt to measure the difference in extractor claw distance.

    It's noticeable, and it definitely was the difference in making this setup function reliably. 380 on the left. 9mm on the right.

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    So to answer Slaine's question, no I don't think that a 380 extractor would work for 9mm. And apparently 9mm extractors don't work very well for 380 either. Kind of makes me wonder why a 'one size fits both' solution is sold given the differences...
    Last edited by tlk; 10-03-2020 at 02:20 PM.

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    Good info.

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