DIY: $10 bump-fire AK stock

Discussion in 'Build it Yourself' started by Boris, Feb 26, 2012.

  1. Boris

    Boris Son of Kalashnikov NES Member

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    This is all legal, … yes, even in mAss. No gray areas or doubts, based on my research. This is an account of my experience meant for your entertainment only.


    • IANAL. You may get sued for a lot of things, like taking a dump in your neighbor’s yard. Whenever you do, get a lawyer and I hope that your defense will be better than “this guy called Boris, on the internet, said it was OK.”


    • I don’t have an ATF letter for this. They are very specific, down to dimensions. Change the screw length and you need another letter. Your firearms do not need an ATF letter of approval to be legal. It’s like asking your dad if you can use his stash of porn. I’m boiling down design on Fostech’s ATF letters of approval, minus dildos and plastic. Dimensions are not the same but the principle of operation is.


    • There are quite a few patents filed in regard to bump-fire stocks. Original Akins’ had a spring … and ATF does not like springs of any kind, especially in a stock. Patent claims may be granted or not, if granted they may still be challenged or invalidated for a whole bunch of reasons like prior art etc. All that said, based on case law, it’s still up in the air if manufacture “not for other’s use” is indeed not an infringement.


    • Bumpfire is not illegal … unless your club sais that it is on their property or your get Fudd attack. It’s like saying that you can **** with your “existing legal equipment” as long as you are making one thrust per three seconds. Trust me, your penis can not just go “full auto”.


    NOW WE HAVE GOOD TIME


    So I talk to Michael Timofeyevich Kalashnikov and he is all bullshit:

    and I’m like

    The foundation for the bump fire stock is railing that allows limited movement in-out without any springs and may not be readily modified to use one. It uses “isometric tension” of your stiff arm to reset the trigger, but you are still firing one shot per pull of the trigger.

    I settled on 5/8” x 10” bolt. We cut its head and its threads. This may run you a couple of bucks.

    [​IMG]


    For the other part of “railing” you need a piece of EMT conduit, I don’t remember the diameter, but it would fit perfectly over 5/8” bolt. It’s $1.50 for 10 feet.

    [​IMG]


    Since we are replacing the stock … stock, we need to make something that would fit into AK’s receiver. I grabbed a bunch metal from scrap heap, stacked it up and welded it together. I also tapped 10-24 holes for screws to hold it in the rear trunnion.

    [​IMG]


    [​IMG]


    [​IMG]


    Now we need to attach the rod to our “trunnion” I used a piece of ½” square tubing to fill in some space in between, then weld … a lot.

    [​IMG]


    [​IMG]


    Time to weld a bunch of crap to the tube. Again, I’m eyeballing scraps of metal and grinding them to size.

    [​IMG]


    The front end gets a M6-1 thread drilled and tapped so that you can attach your regular AK pistol grip. That’s right, I tapped it metric style!

    [​IMG]


    Lower assembly then looks like this. We are almost done.

    [​IMG]


    The tube needs a cut. This cut will hold a rivet that prevent stock from flipping sideways and letting you shoot “hommie style”. It also limits stock travel.

    [​IMG]


    The beefy stainless rivet permanently attaches the rod to the tube, preventing you from slipping a spring inside (i.e. “easily modifying it into a machinegun” – NO!!!)

    [​IMG]


    Rivet is attached half-depth to allow free movement of rod inside of the tube. You are ready to mount the contraption.

    [​IMG]


    At the backside, I drilled a couple of holes on the either side of the tube. The reason for this is that although rod does not have enough seal to create springy piston effect. Remember that spring assist is a no no, so we want to be proactive and make absolutely sure that there is no doubt that nothing will assist in stock return, spring or gas pressure.

    [​IMG]


    [​IMG]


    [​IMG]



    No we go the range. We use the stock on RomyG and and Arsenal AKs.

    Bumpfiring still requires some time to get use to. I don’t get it why you would want to piss away perfectly good rounds. So I am trying to get a hang of this:

    [video=youtube_share;VnbAcU-gF6s]http://youtu.be/VnbAcU-gF6s[/video]


    passing this on to my comrade:

    [video=youtube_share;eGfGYNBHQWA]http://youtu.be/eGfGYNBHQWA[/video]


    [video=youtube_share;vt5Slsd_TYo]http://youtu.be/vt5Slsd_TYo[/video]


    ShadyDuck had some wise words in regard to the limit of stock travel. The optimum travel is about 3/4 “, many thanks to Shady for his expertise and guesting me on his club’s range while I had to make the adjustment:

    [video=youtube_share;axy40GLt0v0]http://youtu.be/axy40GLt0v0[/video]
     
    Last edited: Oct 5, 2017
    13 people like this.

  2. Ryan9896

    Ryan9896 Member

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    Sweet!!! Awesome job, it performed well. A little bit of time to save ALOT of money!!
     
  3. FSTC

    FSTC NES Member

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    Awesome!
     
  4. Twigg

    Twigg Member

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    [​IMG]


    And I mean this in a really, really good way. [smile]

    Do want !
     
  5. Palladin

    Palladin NES Member

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    Good job.! on a $300 POS AK, that's a great modification!
     
  6. xFPS Kyle

    xFPS Kyle Member

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    Wow, props for this. Definitely beats the 300 dollar or so pricetag of the name brand bumpfire stocks. Good work!
     
  7. turbo89

    turbo89 Member

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    Every time I see something like this I have to ask "How is this legal in MA?" I would interpret this as a collapsible stock... so when it's combined with a pistol grip and detachable magazine, it's then an Assault Rifle by the ATF's definition.

    Someone please tell me my train of thought is illogical... because I would love to build / have something similar.
     
  8. shadyduk1979

    shadyduk1979 Member

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    It was glorious fun. I will drink much vodka tonight in celebration of epic win. We build in dark basements and can come up with things such as this.
     
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  9. flintoid

    flintoid Banned

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  10. flintoid

    flintoid Banned

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    then don't build one?
     
  11. Mustad

    Mustad Member

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    Would it be possible to add a lock that allows you to switch from bump fire to single fire? Sorry if this is a stupid question.

    Oh and great job!
    Thanks for posting.
     
  12. shadyduk1979

    shadyduk1979 Member

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    Actually i found that depending on how you pull the trigger it will bump fire or fire one round. Those single shots are not accidents. You can see that i use my left hand to pull the rifle forward, thus bump firing. Then if i fire the rifle normally it fires normally.
     
  13. Boris

    Boris Son of Kalashnikov NES Member

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    what he said, and actually he was banging silhouettes at 100 yards with this "wobly stock", so you still can fire rifle with pretty good accuracy ... at least more accurate than I can.

    I'm still a bit fuzzy on the concept. I guess when bump-firing, your non-trigger arm pulls the stock in a different manner ... it's all Greek to me.
     
  14. shadyduk1979

    shadyduk1979 Member

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    Having shot arsenal AKs before, I don't think it hurt the accuracy at all.
    I was having a bad day though as Boris saw. Shot like crap today.
     
    Last edited: Feb 26, 2012
  15. Twigg

    Twigg Member

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    Install a set screw in the outer tube which screws into a detent/flat spot on the inner rod.

    Hand drill + tap + thumb screw = done.
    Fit a quick throw lever with a pin iffin' you want ssomething a bit fancier.
     
  16. turbo89

    turbo89 Member

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    Aren't you chalked full of good information [rolleyes]... Clearly that's the approach I've taken. The point of my question was to get a reasonable answer; or to have someone point out some major flaw in my statement.
     
  17. atilla

    atilla Member

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    boris you're a genius. unbelievable.
     
  18. edmorseiii

    edmorseiii Navy Veteran NES Member

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    [​IMG]

    Comrade, you are my hero.
     
  19. flintoid

    flintoid Banned

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    Aren't you full of reading comprehension. Read post #1 again, Mr. Rollyeyes. If you weren't too busy worrying about which hand you should pee with, you'd have read your answer already.

     
  20. turbo89

    turbo89 Member

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    At risk of derailing this thread, I'll bite. Where in that quoted text does it answer my question?

    I know the OP isn't a lawyer (and my guess is that neither are you), but the only thing I read in the OP's post that's remotely close to an answer is the reference to the BATFE. I'm specifically about mass-suck-chusetts and not the legitimacy of the OPS design.

    I'm no trying to turn this into an internet pissing contest... but I wouldn't mind getting an answer that adds value to the post.
     
  21. edmorseiii

    edmorseiii Navy Veteran NES Member

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    First line of the first post seems to spell it out pretty clear. If you are worried about it, don't build one.
     
  22. flintoid

    flintoid Banned

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    I give up.
     
    Last edited: Feb 26, 2012
  23. Boris

    Boris Son of Kalashnikov NES Member

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    no need to derail anything, let me chime in.

    IANAL, but this stock that only changes it's length by 3/4" can not be interpreted as "collapsible" or adjustable, the length is never less than 22" of normal rifle requirement. Regulations and case law are indicators what may be interpreted as what, but there is no 100% guarantee. It's probably as legal as any loose stock that wobbles. To be somewhat sure, you may need a letter from an attorney, or better yet AG. There are some attorneys here and hopefully they can state their opinion, however, no amount of assurance would protect you from some enterprising prosecutor who wants to bring charges against you because of this stock or another non-sense like spend cartridge in a fold of your laundry, because they can and sometimes they do. Then it's up to court system. It's a gable. Law get interpreted by people who sometimes make WTF decisions. Obvisouly some gambles are better than others, but the choice is yours.




     
  24. crazymjb

    crazymjb NES Member

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    I love that I proposed this could be built for cheap (granted for an AR) and I was called out barely a month ago. Thanks for proving my point, and good work.

    Mike
     
  25. turbo89

    turbo89 Member

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    Thank you.

    For the record I did read the first line of the post... but your reasoning for not being collapsible was in question. Now that I understand you assumptions you've answered my question to the best of your ability.
     
  26. Boris

    Boris Son of Kalashnikov NES Member

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    haters will hate ... I don't have an AR but I keep checking Plastics recycle bin at my city dump, one of these days ... [wink]


    so what's the challenge here? Is it really legal crap? If not, and people want it, why can't they build it? What's the challenge, laziness? I can see that the stock adapter that holds the bolt may not be widely available, well I can cast a few of those in Al. What else? The other hard part that I can think of is the handle-tube joint. I was thinking about building a Drag type thumbhole stock that would incorporate the tube as well as allowing one more evil feature on your AK since pistol grip goes way. Now you have a bump-fire AND one more evil feature. Please clue me in, why I only hear single shots when I'm driving by my range?
     
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  27. Twigg

    Twigg Member

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    The "challenge" is nanny state girly men with low self esteem who see something they think *might* (Because they do not like it.) not be permited in their socalist utopia. So they run in circles flapping their arms screaming "The sky is falling!" and attempt to get all other slaves of state frightened of losing their "suitability" and spoil fun for everybody. [frown]

    The reason you only hear single shots when driving by range is you live in the wrong state. I can hear full auto fire (the real kind not make-believe) on weekends from neighbors shooting in their backyards.

    This is the sound of freedom and why New Hampshire is the "Live free or die!" state.[smile]
     
    Last edited: Feb 28, 2012
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  28. Boris

    Boris Son of Kalashnikov NES Member

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    I was afraid of that answer, we can fix technology but you can't convince men that they are free. I'm sad to see people afraid to fart, even though it's legal, just because they don't have an explicit approval from AG to do so. We got a lot of "nation building" to do here, starting with democratic elections etc. [smile]
     
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  29. shadyduk1979

    shadyduk1979 Member

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    I was thinking of that. I have a old thumbhole stock from my BWK-92 collecting dust in my closet that i was thinking of putting one of these into and actually making it useful. Those thumbhole stocks can be had for around the same cost as a pistol grip if you dig hard enough.

    Edit: Grabbed my thumbhole stock. There is a ton of meat to do this. Bore a hole here where it used to meet the receiver for the tube.
    [​IMG]
    Put grommets around said tube so there is room for the rivet to move and not jam up. Pin the back of the tube so it is secure. Open up this section at the top where it used to bolt in so that the plate that bolts to the rear trunnion can be mounted securely on a piece of square stock, yet not as noticeable when looking from the side of the rifle.
    [​IMG]

    Then presto you have a bumpfire stock that looks decent, and you have actually used that stock you had no use for but just couldn't throw away

    For those who cannot visualize and can bear with a terrible drawing, here ya go
    [​IMG]
     
    Last edited: Feb 28, 2012
  30. Boris

    Boris Son of Kalashnikov NES Member

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    that's awesome, where do you get that cheap thumbhole stock from?
     

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