SP5 Modifications for SBR?

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  • ken792

    Ultimate Member
    Sep 2, 2011
    4,467
    Fairfax, VA
    That is eleven set of DIY prints, now I have ETF for others in the future.
    You only have to submit two cards per envelope, no limit to how many application cover sheets you include with each envelope.

    The EFT is certainly convenient. I just don’t want to spend money for clear prints they don’t even want.
     

    dc1818

    Member
    MDS Supporter
    Oct 12, 2023
    1
    United States
    Time for me to go public. I mentioned it to a few people at the MSI fundraiser yesterday. I've been working on an adapter for the new collapsible Magpul SL stock. I designed a spacer (about 2.75") to hit 29". Ok, so this is like all the other long LOP solutions? Nope! It can work like what I did for the MPX. I can cut another notch in the slider to stop about 2.75" shorter and maintain the orig LOP yet still be able to extend to 29".
    Right now the spacer is only 10mm as it prints quick and I'm dialing in the fit on both sides (It's a PITA to fit all the curves and bends in the Magpul stock!) Have gen 5 on the printer now and I think it should be the one. Then I'll stretch it to the required length and print the first full length one - tomorrow hopefully. I still need to source screws but I have an idea for that.
    One of the benefits is that as an extendible stock (and not a folder) it's not an evil feature and you can still use a suppressor.
    Hey did you ever get around to finishing this modification I would love to purchase the model file so I can print it myself.
     

    Ghostrider1

    Ultimate Member
    Nov 10, 2009
    1,889
    The PGC
    Finally found an option that is aesthetically acceptable. Jmac custom ST-6 skeletonized folding tube and 1913 end cap, YHM .5” x 1.25” riser, Battlelink minimalist stock. They make a fixed tube option if you don’t want a folder. Gets to just under 29.25 fully extended.
    IMG_6410.jpeg
    IMG_6409.jpeg
    IMG_6408.jpeg
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,609
    MoCo
    Could add an intermediate notch to make the LOP anything you like. Its actually kinda usable in the collapsed state too even w/ my long arms & neck. Needs a coat of black textured paint to match.
    PXL_20231108_mp5extended.jpg

    PXL_20231108_mp5collapsed.jpg
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,609
    MoCo
    Is that the 3D printer mod on a magpul stock? I like it.
    Yes. It took a lot of modeling to get the interfaces right. The project started as a buttstock pad spacer but once I figured out the rails came off the other end I scraped it and designed this. Looks much nicer than a blocky space.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,624
    Bel Air
    Yes. It took a lot of modeling to get the interfaces right. The project started as a buttstock pad spacer but once I figured out the rails came off the other end I scraped it and designed this. Looks much nicer than a blocky space.
    Looks good!
     
    Could add an intermediate notch to make the LOP anything you like. Its actually kinda usable in the collapsed state too even w/ my long arms & neck. Needs a coat of black textured paint to match.
    View attachment 439588
    View attachment 439589
    OK, the loaner you handed off today fits my AP5 like a glove. After I do the torture test on this, I will be needing one of these in my life.
    It turns a MKE AP5 to a 29.1" SBR.
    .
    ETA- It is already a MD compliant registered SBR. The Magpul stock with the Smdub spacer looks very HK-esque vs my existing AR adaptor to get to 29".
     
    Last edited:

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,609
    MoCo
    Should make any standard MP5 (or clone) w/ 225mm/8.9" barrel over 29". Basically anything w/ the barrel sticking out past the handguard whether just 3-lug or the Navy 3-lug+thread.

    I'm not aware of any MP5s that didn't have a 3-lug barrel sticking out past the handguard. If they do exist, I could print a slightly longer spacer to accomodate.

    It will *NOT* work on the MP5K guns. They can't use the HK collapsible stocks anyway as the endcap is different (2 pins) and also have the reinforcement tabs on the receiver blocking the rails.
     
    OK, the loaner you handed off today fits my AP5 like a glove. After I do the torture test on this, I will be needing one of these in my life.
    It turns a MKE AP5 to a 29.1" SBR.
    .
    ETA- It is already a MD compliant registered SBR. The Magpul stock with the Smdub spacer looks very HK-esque vs my existing AR adaptor to get to 29".
    @smdub
    I took it out for a torture test today and it worked like a champ. Your spacer is plenty strong even when shooting hot loads. (I was shooting 124gr @ ~1300fps)
    .
     

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    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,609
    MoCo
    Good to know. Thanks! That one was really just for fit testing. It's PLA w/ 6(?) walls and only 20% infill. I'm still thinking I should get some of these printed out of nylon.

    Are folks interested in a run of these?
     
    Good to know. Thanks! That one was really just for fit testing. It's PLA w/ 6(?) walls and only 20% infill. I'm still thinking I should get some of these printed out of nylon.

    Are folks interested in a run of these?
    I am 100% interested.
    I received my stock yesterday and also want to cut a few more notches. The LOP was a little long, even with my gorilla length arms.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,624
    Bel Air
    Good to know. Thanks! That one was really just for fit testing. It's PLA w/ 6(?) walls and only 20% infill. I'm still thinking I should get some of these printed out of nylon.

    Are folks interested in a run of these?
    Yessir.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,508
    Good to know. Thanks! That one was really just for fit testing. It's PLA w/ 6(?) walls and only 20% infill. I'm still thinking I should get some of these printed out of nylon.

    Are folks interested in a run of these?
    I would be, just to have.
     

    wreckdiver

    Ultimate Member
    Nov 13, 2008
    2,912
    Yes. I’ve been hesitant to pick up an ap5 cause I didn’t want to use it as a pistol. It needs to be an sbr.
     

    chslax10

    Member
    Feb 27, 2013
    58
    Good to know. Thanks! That one was really just for fit testing. It's PLA w/ 6(?) walls and only 20% infill. I'm still thinking I should get some of these printed out of nylon.

    Are folks interested in a run of these?
    I would definitely be interested in one. Looks great.
     

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