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Thread: BLOW BACK IDEAS W LESS AK PARTS

  1. #11
    Gunco Member deth502's Avatar
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    the gun is not 100% finished yet. needs some finishing touches yet, but it working 100%

    i have build threads going at homegunsmith.com and on the prexis forum weaponsguild.

    i know you have to register to see the pics on weapons guild. the posts in the home gunsmith, im not sure if you just need to be a free member or a subscriber to view.

    plan on posting pics around the net when its done, but th ats where the actual build thread is.

  2. #12
    Gunco Member deth502's Avatar
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    oh, btw, its a take off of the sgn 9 atricle in shotgun news. i though that it was a great idea, but poorly executed. i tried to go with his idea, only make something "nice"

    search for "sgn-10"

  3. #13
    Gunco Member deth502's Avatar
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    btw, if your interested, i think i did a little bit of a write up on the 9mm ak pistol on weaponeer. its in the home build challenge. the first one. i know you dont have to register to see that thread.

  4. #14
    No Hope For Me 1biggun's Avatar
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    were you able to mill the bolt with out softening it?????. I plan to do a semi Sunomi at some point. once the AK kits are gone.

  5. #15
    Gunco Member deth502's Avatar
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    i did anneal the bolt. and i felt no need to try to reharden it after. there are absouloutley no signs of battering, and its no softer than my chamber/trunnion area that its stopping against.

    did i HAVE TO anneal it?? i dont know. it may have machined with carbide tools before. i did turn the outside down as suggested int the sgn9 article, for the whole, fa bolt cant fit in think, but after i though about it, and i dont know if that was 100% nessicary. yes, a fa bolt can fit into a semi suommi build, but i wasnt building a suomi.

    the milling went very easy (with hss mills) . the turning was a little hard (with carbide).

    the annealing wasnt hard. i just got it cherry with the oa torch, held it there for about 45 sec-1min, and set it down to cool. i didnt keep it warm to slow the cooling much.

  6. #16
    No Hope For Me 1biggun's Avatar
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    thanks for the info.

  7. #17
    Gunco Veteran muttman's Avatar
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    Quote Originally Posted by 1biggun View Post

    I was actually considering making the sunmoi bolt square and converted to semi auto fire bolt closed and running it in a AK reciver.
    what is the point of using a closed bolt? 1mil sub guns cant wroung.
    muttman

  8. #18
    Gainesville, Ga Prototype Services's Avatar
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    Federal law. Has to be closed bolt.

  9. #19
    GuncoHolic kernelkrink's Avatar
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    Some random thoughts on the subject.

    The Thompson type bolt would be easy on a lathe, the front part is a simple round rod shape with a breechface machined into the end. Some of the "sorta Tommies" produced back in the 70s and 80s used a simple spring steel extractor screwed to the outside of the rod instead of the machined pocket on the real Tommy. Most of these were tube guns, the rear section was round also instead of rectangular/square. Some were two piece, with a pin or weld holding front and back together. Would be an easy way to go from round front to square back.

    The Greasegun used twin guide rods passing through the bolt to allow the bolt to travel back and forth, the Remington 597 also uses this system. Allows a bolt to be any shape as long as it fits inside the receiver, no guide rails needed.

    The AK hammer is almost the full width of the receiver at the "wings" where the trigger and disconnector hold it. One of the reasons the recoil spring is mounted high instead of inline with the bolt. Eliminating the carrier and gas tube might require the spring to be mounted lower, interfering with hammer travel.

    A narrow hammer such as the AR15 or Remington 870 type would alow more design leeway, one could even slot a "window" in the bolt for the hammer to enter instead of limiting bolt length to be in front of the hammer when in battery. Also would give clearance for twin recoil springs on guide rods.


    "Limits" on blowback have more to do with size and weight of components rather than pressures. The HK G3 rifles are a roller delayed blowback action. I forget the exact numbers, but a .308 rifle would require a 30-something pound bolt in order to function as a straight blowback. The roller mechanism on the Hk creates a "mechanical disadvantage" so the rearward pushing cartridge case isn't inhibited solely by the inertia of the bolt and carrier. This lets them drop the bolt/carrier weight and size to something practical for a shoulder fired weapon. They also use a fluted chamber so gas from firing can "float" the case within the chamber, otherwise the case would stick to the walls and prevent operation.

    AMT made a .22 magnum rimfire pistol, IIRC they had to machine rings into the chamber so the case would swell into them to delay blowback.

  10. #20
    No Hope For Me 1biggun's Avatar
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    Kernel there are some really good ideas in your post. Thanks.

    looking at the .22LR trunion it seems that the the barrel is raised up around a 1/2 inch as well as the bolt face. I suspect a
    9mm blow back bolt mimicking the german 22lr might be able to do the same thing. with out doing major changes to the FGC ,you are correct the hammer will hit the spring. It does apper that if one side of the hammer were removed an a single hook trigger were used, the spring would be very close to fitting along side it.

    Your idea of a hammer through the bolt is one that would allow putting the barrel and spring inline. I will have to think that one over seriously.

    I will have to find some good picks of a Thompson bolt. Did the Thompson use a rail type ejector? or was the ejector in the bolt?? ANYONE GOT ANY THOMPSON PICTURES??????????

    It has also occured to me that if a new trunion and bolt were made I could shorten the reciver at least 2" possably more for a 9mm. something that would be really nice for a pistol build.

    Getting weight in the bolt might become a issue as well. Im sure lead could be added if nessacry.

    Deth502 is correct this is starting to be more and more like a scrath build. especialy if i want a lower sight plane.

    I still think at least doing a new front trunion is a good idea even if everything else is left alone.

    the rings in the chamber is interesting. I want a 17 hmr SA rifle (not a HMR2) and that might be usefull in a build. The 10-22 magnums are way to expensive to buy and convert.

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