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Thread: 7.62x25 Gas Operated AK pistol

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    Gunco Member SW44's Avatar
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    Default 7.62x25 Gas Operated AK pistol

    It ain’t done yet but its working great, so I couldn’t wait to unveil. Most of the parts are from an AMD 65 AK47. The bolt and carrier are from an AK74. The barrel and mags are from a PPSH 41. The magwell is from Lichtenberg. The flash hider is from an L1A1.


    Here are the details.

    Barrel It is a PPSH 41 barrel. The rear of the barrel was turned down and sleeved (and a tack weld) to fit the AMD 65 front trunnion. Another sleeve was installed for the rear sight block. The barrel was turned to fit the gas block and front sight block of the AMD 65. A sleeve was added to the barrel in front of the gas block to fit the front hand guard retainer. The barrel was threaded for LH 14x1 threads. A cut was taken from the chamber end of the barrel for extractor clearance. Minor radiusing of the lower half of the chamber lip was done after a round caught on it during testing. The gas vent hole started at 0.125” and grew to 0.170” during testing.

    Flash Hider I drilled out an L1A1 flash hider and pressed in a steel bushing. The bushing was then drilled out to 13 mm and tapped for LH 14x1 threads.

    Receiver I traced an AK Builder flat (love your flats man!) onto 0.040” thick 4130 steel and cut out everything but the magwell. I did some measurements and hacked out my estimate of the opening. I bent the receiver on my own jig. The magwell opening was cut too big as was as the back clearance notch for the bolt carrier. A new receiver is planned before final finishing.

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    Gunco Member SW44's Avatar
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    Fire Control Group AMD 65. The hammer face and top were reprofiled to reduce force needed during recoil to recock hammer. Lots of experimental welding and grinding. A reduced force hammer spring was made using 0.045” diameter music wire bent to the stock configuration but with only one leg.

    Bolt Stock AK74

    Bolt Carrier It is from an AK74 with 1 inch of length removed from just behind the piston threads. The carrier was welded back together using a brass rod inserted to align the pieces before welding. The carrier and piston assembly was shortened because I moved the gas port closer to the chamber to tap into higher gas pressure. The photo shows it compared to a standard bolt carrier.

    Gas Piston Custom made stainless steel one inch in length (not counting threads) The clearance between the gas piston and gas block is about 0.005 inches.

    Recoil Spring During testing, an inch at a time was removed from the recoil spring until three inches was removed to reduce the force exerted on the bolt carrier. The metal loops that retain the spring were shortened to reduce the overall length of the assembly and fit it to the shortened bolt carrier.

    Gas Tube Custom machined tube with the locking ring from an AMD 65 gas tube spot welded on. The majority of the tube interior diameter is for the large diameter of the bolt carrier. An interior taper is machined on the front end to guide the gas piston to the gas block. The gas block vent holes are only partially obscured.

    Front Trunnion An AMD 65 trunnion was cut to fit the mag well up close to the barrel throat. (The photos show the cutting and fitting) Cuts were made using a 4” thin abrasive disk on a hand held grinder. A stream of water was used to keep the trunnion cool and maintain the trunnion’s heat treatment. The cuts did not go up into the locking lugs. The bullet guide was removed and ground so that the AK74 bolt could rotate up the left side. ( The AK74 bolt head has a greater distance from the back of the locking lug to the front of the head than the AK47.) The guide was riveted back into place and later tack welded when the cuts to fit the mag well cut into the rivet area.
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    Last edited by SW44; 03-29-2009 at 04:06 PM. Reason: enhanced spring description

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    Gunco Member SW44's Avatar
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    Mag Well The mag well is a 7.62x25 assembly from Lichtenberg Research. A large relief cut was made on the top right front so that the mag well mated up tight against the right front trunnion locking lug. A lot of the mag well’s feed ramp was ground down for clearance as the bolt rotates into the locked position. I am not sure the rounds touch the feed ramp on their way into the chamber. Miscellaneous other filing, grinding, etc. was required to fit the mag well.

    Gas Block The AMD 65 gas block was used. The block was mounted to the barrel so that the rear of the gas block is 4.94” from the chamber face of the barrel. That places the gas port about 5.30” from the chamber face of the barrel.

    Rear Site Block The AMD 65 rear site block was cut so that the block could be moved as far back as possible and still eject shells. I should have only cut the right side of the block, but in my enthusiasm I cut the left side as well. When I shortened the top cover I left a “leg” to fill the gap I created on the left side.
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    Last edited by SW44; 03-11-2009 at 07:53 PM. Reason: added photos

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    Gunco Member SW44's Avatar
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    Lower Hand Guard The stock AMD hand guard was cut in length so that the hand guard retainer would be located just in front of the gas block. The rear mounting tabs were spot welded back in and the front grip mounting hole was filled in with a piece of sheet metal MIG welded in. After the gas block was installed on the barrel, a sleeve was pressed onto the barrel to provide the correct diameter for the hand guard retainer.

    Trigger Guard Since the mag well is shorter in length than a standard AK mag well, I made a longer trigger guard out of 0.050” thick 4130 steel. I didn’t want to tear apart a good AK trigger guard so I also made a mag catch lever and spring. The spring was made from 0.045” music wire. Because the mag catch lever was so far forward, I placed a small block of steel between the mag catch and the trigger opening to give a surface for the mag catch spring to push against. This steel block is held in place by two button head screws at this time.

    Rear Trunnion The AMD trunnion was used. A steel plug was milled to fill the mounting hole for the original folding stock. With the plug clamped in place, a hole was drilled vertically down through an existing hole on the right side of the trunnion and the plug was pinned in place. A quick weld ensures it isn’t coming out.

    After a lot of fitting and testing, the action is cycling perfectly with drums or stick mags. Test firing was done with surplus Chinese ammo and some Sellier & Bellot ammo. Accuracy seemed good at the pistol range. The front sight was stuck and I couldn’t adjust the impact point at the range. I fixed it when I got home and look forward to getting back to the range.
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    Indian Admin Winn R's Avatar
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    Wow!!!!

    That's what I call building one from scratch!!! Well done.
    There is no nonsense so errant that it cannot be made the creed of the vast majority by adequate governmental action. -- Bertrand Russell


    "Never attribute to malice that which can be adequately explained by stupidity." Robert J. Hanlon

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    Gunco Member Duster.'s Avatar
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    Thats a Dream.. Perfect fit with a CZ 52 as a back up
    Very cool build....
    Indifference to Evil is Evil!

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    Gunco Member petro116's Avatar
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    Very cool.

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    Gunco Maniac sjohnson's Avatar
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    Ought to be proud! Very nice, and thanks for sharing details and pictures!
    I have a daughter. I tell her, "911 is what you dial after you're raped. 1911 is what you should have before they try."

  9. #9
    No Hope For Me 1biggun's Avatar
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    VERY NICE CAMERA WORK AND WRITE UP. NICE BUILD. AS SOON AS i DIGEST ALL THE WORK DONE ILL HAVE SOME QUESTIONS. THERE IS A SIMULAR BUILD OF SOME TYPE IN MY FUTURE. I WAS ORIGINALY THINKING 9MM BUT THE 7.62X25 HAS REALLY GOT MY ATTTENTION. I REALLY LIKE HOW YOU GOT THE MAG WELL UP CLOSE TO THE BARREL BY MODIFING THE TRUNION REMOVING THE FEED RAMP ECT.

  10. #10
    Gunco Member Bullpup's Avatar
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    Really impressive build, great writeup too! are you concerned about cutting into the trunion that much/ worried the locking lugs are not supported enough without the rest of the trunion? In any case, it does solve the magazine gap issue I'm facing. Don't mean to hijack your thread, but I'm building a 7.62x25mm gas op too:


    here you can see the gap:


    the rounds reach the end of the feed lips and still have almost a 1/2" to go before entering the barrel. Your 2xtm magwell placement eliminates that problem.

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