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Thread: CETME-47 (CETME in 7.62x39)

  1. #31
    holescreek's Avatar
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    Cycling by hand is using the extractor claw to pull the round from the chamber and that's not it's usual job. On these rifles the extractors only job is to hold the cartridge into the bolt head recess long enough for the ejector to kick it out. The difference is that when firing, the cartridge is removing itself from the chamber at a high rate of speed, the extractor isn't pulling on it. You probably won't have any extraction issues from firing. One of our old members used to have a video on youtube firing multiple shots with the extractor removed from the bolt head.

    On my x39 build I ground the base of the extractor claw (where it slides into the groove in the bolt head) in order to allow it to drop in a little further and grab the rim a bit more.

  2. #32
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    Quote Originally Posted by holescreek View Post
    Cycling by hand is using the extractor claw to pull the round from the chamber and that's not it's usual job. On these rifles the extractors only job is to hold the cartridge into the bolt head recess long enough for the ejector to kick it out. The difference is that when firing, the cartridge is removing itself from the chamber at a high rate of speed, the extractor isn't pulling on it. You probably won't have any extraction issues from firing. One of our old members used to have a video on youtube firing multiple shots with the extractor removed from the bolt head.

    On my x39 build I ground the base of the extractor claw (where it slides into the groove in the bolt head) in order to allow it to drop in a little further and grab the rim a bit more.
    That is what I figured but it is good to hear someone with much more experience with these guns say it.

    Do you have a picture of your ground extractor you can share? I might end up grinding mine down as well just to help with manual extraction and ejection so I don't have to flip the gun and shake every time.

  3. #33
    holescreek's Avatar
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    All the photos that still exist are in this thread starting at post #24: http://www.militaryfirearm.com/Forum...=7.62x39+cetme

    I had two Cetme builds going on at the same time and was very new to the platform. It's one of those builds that I should consider remaking now that I know a little more about them. The other gun built at that time (my GHG1) was rebarrelled a couple years ago and got a proper tune-up.

  4. #34
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    Quote Originally Posted by holescreek View Post
    All the photos that still exist are in this thread starting at post #24: http://www.militaryfirearm.com/Forum...=7.62x39+cetme

    I had two Cetme builds going on at the same time and was very new to the platform. It's one of those builds that I should consider remaking now that I know a little more about them. The other gun built at that time (my GHG1) was rebarrelled a couple years ago and got a proper tune-up.
    Thank you for the link. luckily the photo of the extractor survives and I was able to figure out how to rework it. I have seen a few of your CETME builds pop up on here, always great looking guns.

  5. #35
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    As mentioned here is the progress of the magwell insert for using AK mags. And before you ask, yes I will be posting the STL, No, it will not be anytime in the next few weeks. I want to test fire the gun and make sure it all works properly first.

    This post is more for the Photos but here is the list of design changes I made between versions, these are my notes to self so I know what changed with each edit.

    IMG_20210507_161536483.jpg

    V2- Widened magwell hole and removed inner mag profile.
    V2.1- Slimmed insert, removed excess material
    V2.2- Moved trunnion lip up .5mm, increased fillet radius on back of insert to 7mm
    V2.3- Redesign front lip to add step down. Inner mag well sweep removed
    V2.4 Widened back groove added angles to better fit different mags. Added back area for cross pin. Extra area for mag release lever.
    V2.5- Extend Back mag catch chamfer up 2 mm, move chamfer in 1mm. Extended top of catch lever up 1mm added chamfer to where mag rests, extended length 5mm. Narrowed back of Mag insert fin to 14.5 mm. narrowed hole to 10mm, thinned mag catch lever to 9mm.
    V2.6- Rework front profile of catch lever moving top front chamfer down more. Open opened mag catch hole back up to 11mm. shortened mag fin from 15mm to 10mm.
    V2.7 added slot in back of catch area for cross bar that holds insert in place. Made front mag catch lip larger for better catch flattened top section. Made chamfer in back slot taller to 8mm and more shallow by 1mm. Slightly thinned front of mag catch lever between pivot hole and where mag catch rides. Lower mag catch pivot point and extended top of catch lever 3.5mm To make room for mag catch spring. Added spring divots to insert and lever to hold spring. Deepened pocket to make more room for spring.
    V2.8 moved catch lever and back spring divot down 1mm. Changed front mag lip back to old style. Added chamfer behind back crossbar slot to strengthen area.

    As of right now V2.8 is what I have in the gun and is what the close up pictures are of. It feeds rounds out of the mag very well and holds everything in the gun nice and tight. The insert rocks in like a regular G3 mag and uses the front trunnion lip to hold the front in. The back is held in by what will be a split bolt (now it is just a machine screw and nut) through the existing holes of the mag catch. This keeps the top profile of the insert flush with the top of the area where the mag catch lip is. The AK mag catch pivots on a 1/8" pin and is pushed forward by the CETME mag catch spring from the parts kit. AK mags rock in and out clean with a nice click when seated all the way. There is just a little bit of wobble up and down in the front of the mag but I am not worrying about it right now. I have a few new Bulgarian steel AK mags I bought for this build and they fit great. I also have a unknown maker steel mag that the rear lug is about .5mm too long so it won't rock in and a AC-unity polymer mag that is just too big all over to fit. Barring any major failures or issues while testing, this will probably be the final version as I do not plan on making any revisions to accept polymer mags.

    IMG_20210507_161740964.jpg
    IMG_20210507_161831871.jpg
    IMG_20210507_162107774.jpg
    IMG_20210507_162220787.jpg

  6. #36
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    Nice work!
    14EH AIT Instructor-PATRIOT Fire Control Enhanced Operator/Maintainer

  7. #37
    holescreek's Avatar
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    I love it! Someday I'll muster up the skills to make good 3D drawings for my printer. I've fumbled around with it in Freecad but don't stay with it long enough to get good at it.

  8. #38
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    My freecad skills are definitely night and day compared to what they were a year ago. I would say I know enough to be dangerous but not enough to be efficient.

  9. #39
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    Did some hand milling over the weekend/ past few days and put the finishing touches on the rear sight V2. This design is more like the G3 and uses a 10-32 cap head screw to move the base the CETME rear sight is welded to. Overall it raised the rear sight up about 1/4" so I am not sure how much I am going to need to take off the front but luckily I am changing that to take a standard ar-15 front post and should be able to easily shorten them as needed.

    IMG_20210516_100627262.jpg

    Attachment 58129

    IMG_20210517_084301632.jpg

    IMG_20210520_221934707.jpg

    IMG_20210520_221959373.jpg

    It's ugly but I am pretty sure it'll get the job done.

    All that I have left to do before test firing is modify the triple tree, solder the triple tree in, and finish the front hand guard. If all goes well after testing I am going to clean all the welds up and get it parked.

  10. #40
    holescreek's Avatar
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    Will you have to raise the front sight the same distance as you raised the rear?

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