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Thread: Future build - Cetme in 7.62 X 39 Things to consider?

  1. #21
    Senior Veteran bladeworks123's Avatar
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    Looks like PTR has figured out something with their new PTR 32.....

    http://www.ptr91.com/ptr32.html

    Might have to get one just to see what's going on.
    BATTLEMENT ARMS
    www.battlementarms.com

  2. #22
    holescreek's Avatar
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    Yes, I was reading about some of it in the links Smokehouse69 posted. There is/was a huge drama regarding the AK mag adapter between PTR and Hart1. I read all of the links in one sitting plus some searches of my own that night so I don't remember where I saw it, but the ad is apparently a little premature, possibly to stir up interest. But hey, if you do get one, I'll be waiting on some of the dimensions!

  3. #23
    Veteran texlurch's Avatar
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    HKparts had the PTR-32 kit for sale, and then pulled it after I placed my order... been waiting for 6 months now, and last word I got is they are going in production and the bugs are worked out. So hopefully I'll get the parts one of these days..

    It uses a different barrel, dedicated receiver with AK magwell and catch, a different bolt head, new triple frame, and the rest is standard G3.

    After shooting the HK-93 I built, I just figured the 7.62x39 would be a great round for this system. What the heck.. already have an AR in 7.62x39 as well..
    There is always room for another AK or 1911.

    As with anything car or gun related, your results may vary!

    "There has been a disturbing increase in things I know nothing about."

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  4. #24
    holescreek's Avatar
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    I had to dig this old post up to provide an update. Hopefully a moderator could move it over the the "build it yourself" section where it belongs.

    I ended up using an RPK heavy barrel for this project. It left plenty of meat to turn down to fit the cetme trunion. I faced the ejector slot off the back, reamed the chamber deeper to bring it back into spec. A few hours on the CNC netted me a useable x39 barrel.

    rpdbarrel003.jpg

    Next I had to modify the extractor to move it inward to catch the smaller diameter rim. I ground on the extractor where it fit into the slot on the bolt to allow it to drop in .010" further. Because it rides in an angular groove, it raises towards the bolt face as it closes in. I had to regrind it flush to the face after the modification.
    boltmods1003.jpg
    boltmods1009.jpg


    Once comfortable that everything was safe, I pinned the barrel and moved on to the mag issue. I wanted to use AK mags so the first thing to do was figure out how to position, then hold them there. The front tab on the AK mag just barely grabs on the tab at the back of the cetme trunnion. I made a spacer to add more of a shelf for the tab and center the mag in the front.

    Edit: Original photo unavailable until I locate a copy
    maghook004.jpg

    Then I made some spacer plates for the mag well sides and plug welded them into place. Next was a latch for the back tab. The receiver I used was one I had made for my BATF submittal so it already had a paddle mag block in place which made a great pivot point for a rear latch.
    Edit: Original photo unavailable until I locate a copy


    I'll weld over the pin when I do all of the other welding. I have to make new side plates for the outside of the mag well and fill the extra holes from the old mag release.
    Attached Images Attached Images
    Last edited by holescreek; 02-10-2021 at 07:39 PM.

  5. #25
    holescreek's Avatar
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    Ctubesupport008.jpg

    I really like the fins on the RPK barrel so I want to build them into the design. I shortened the cocking tube up 3" and made a fake AK gas block to hold the tube in place.
    Ctubesupport005.jpg

    Here's where I'm at so far:

    Ctubesupport004.jpg

    I have a cone shaped flash suppressor on the drawing board to fit over the 9/16-24 threads I turned on the shortened 18 1/2" barrel. I need to figure out a front sight and short hand guard, preferably something with a vertical fore grip. Preliminary tests with the firing pin removed have the bolt stripping a cartridge out of the mag and chambering, and the extractor successfully pulling the cartridge back out. I'm anxious to get everything welded up for a range test but know there's too much left to do mechanically to lock everything down yet. Stay tuned. -Mike
    Last edited by holescreek; 02-10-2021 at 07:43 PM.

  6. #26
    Senior Veteran Smokehouse69's Avatar
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    Looks very good Mike! I am really, really starting to like this build a whole bunch! I know it's going to turn out spectacularly!
    COG Member #1069

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    and this I shall never submit to." Horatio Lord Nelson

  7. #27
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    looks good

    now if you add an AR site you've got it all covered, cethkarak

  8. #28
    holescreek's Avatar
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    I had to do an advanced search to locate this old thread. I have some time to kill before my 80% FPK receiver arrives so I figured I'd jump back on this build before I start on another platform.

    A night or 2 ago I gathered up all the parts for this rifle that I could find and started the build in earnest. I got all the welding done Sunday night and discovered on Monday morning that I had used the trigger pack for something else. Luckily I had enough parts laying around to build another one and I was off an moving again.
    cetmebolts001.jpg

    The "trick" is to figure out what I need to to make this gun cycle. Sunday I spent a couple of hours trying to get the action to cycle. The standard x51 parts are way too stout for the little X39 round. First problem I had was getting the bolt to unlock. I started trying to loosen things up by taking half a coil off of the bolt retainer pawl spring and polishing the contact surface on the pawl and the bolt. It helped a little bit, I can now assemble and disassemble the bolt without any tools! After some test shots I decided that
    more had to be done. I finally decided that the standard 50 degree LP had too much travel and there just wasn't enough power to push the bolt all the way back to allow it to unlock. I blued up the LP and set it back up in the rifle. I let the bolt fly home a few times to mark the spot where the rollers came to rest at lockup.

    x39bolts002.jpg

    I dusted the flat sides of the LP on the surface grinder just enough to make them parallel, then set the LP up in a grinding vise on a sine plate to grind the LP angles to an included 65 degrees up to the roller lock-up point. I did it that way so I could keep my original .016" bolt gap while still getting quick release of the rollers.

    x39bolts003.jpg

    I made a couple of test shots and saw that the bolt was now unlocking but immediately being slammed home by the original recoil spring.

    This morning I started trimming the recoil spring trying to find the sweet spot where the bolt would come back far enough to eject and the spring would have enough left to send the bolt home. I should have taken my cuts in smaller increments but I started by taking 3" off, then another 2 1/4". With 5 1/4" off the gun cycled fine, stripping the first round off of the AK mag. I had to add about 1/16" of weld to the top of the ejector so it could reach the smaller diameter case rim, but it works and kicks them right out.

    The only problem I'm having now is getting the bolt to strip the second round out of the mag. It seems to like the position of the 1st and 3rd round (on the same side of the mag) but doesn't like even numbers. I started working on better mag positioning before I had to stop to go to work.
    Last edited by holescreek; 02-10-2021 at 07:49 PM.

  9. #29
    Senior Veteran Mortal_Wombat's Avatar
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    holy crap
    your builds blow my mind.
    and that gun just looks diabolical
    Who knew that buying a m44 mosin would start an addiction?

  10. #30
    holescreek's Avatar
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    A parts kit is available for the PT-32 for $479 it includes a new receiver, bolt, locking piece, mag and barrel:
    http://www.calguns.net/calgunforum/s...d.php?t=319651
    The parts in the kit are all you are supposed to need that are "special" to the x39 round. Their site says all the rest of the parts are standard HK91.

    I just ordered some Tapco 20 round mags for mine tonight. I have everything functioning but the feeding. I suspect (hope) the plastic mags might be the key to that issue. Extending the feed lips on my old worn out AK mag hepled but isn't consistant. I'm up to a little over 25 rounds through it so far, a couple were even shot in a row!
    Last edited by holescreek; 07-15-2010 at 10:41 PM. Reason: spellin'

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