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Thread: Help- Won't Lock Up

  1. #1
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    Help- Won't Lock Up

    Hi, first post for me. Bought a Century CETME (not C308) from what was supposedly built in late 90's or early 2000's. Brought it home and it cycled fine a few times then I noticed a washer fell out that I'm 80% sure it fell out of the front-end of the inside of the cocking tube. It was previously epoxied in there to act as a shim. Without it, the bolt completely locks up and I can't cycle it without using a hammer to the cocking lever. I have to tap it hard enough to unlock but not hard enough that it'll bend the cocking lever. Anyway, I epoxy that washer/shim back in (measures 1.86mm in thickness and 15.96mm in diameter) to the front inside of the cocking lever. Now the cycling works but somehow, the bolt doesn't actually lock up. There's this giant gap (see pic) betw. the bolt and the carrier. I can see that the rollers are sitting in the recesses of the trunnion where it should be but it doesn't lock up as I can see thru the magwell that the rollers are loose and just 'flop' around in the trunnion. Not sure what is going on. Please help!

    Cetme issue.jpg

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    Senior Veteran SgtHorvak's Avatar
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    I'm a rank beginner to this CETME (DRB)game with only one completed build under my belt, but it sounds to ME as if that washer/shim shouldn't even be in there in the first place, and someone tried to artificially adjust bolt gap/cocking tube gap and/ or adjust for an incorrectly pressed/pinned barrel installation with it. Since you evidently have WAY too much cocking tube gap without the shim, and are way short of having a correct bolt gap with it, it sounds to me as if you need to measure each of these parameters without the washer/shim, which I don't believe belongs there in the first place. You may either have a bolt carrier arm (the part that extends into the cocking tube) that is too short, or incorrectly installed cocking tube during the build. Others here with vastly more experience than I have will probably have the solution. I wish you good luck!!
    Last edited by SgtHorvak; 05-05-2019 at 07:18 AM.

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    holescreek's Avatar
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    The washer was probably glued onto the end of the carrier tube to overcome either a short ground tube or a too-long cocking tube placement.

    It sucks that you got stuck with someone else's experiment unknowingly. Unless I'm mistaken it appears that you got a cast stainless receiver there so it will be worth your time to determine the problem. Cast models are not known for misplaced cocking tubes so it might just need a new carrier.

    If you are willing to take some measurements we can get this sorted out. Ideally I'd like to know the length of the carrier tube, length of the bolt head, and the bolt gap with the cocking handle support removed. Eventually I'll want pics of the locking piece shoulders and the front edge of the bolt head windows, but it might not come to that.

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    Senior Veteran SgtHorvak's Avatar
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    Quote Originally Posted by holescreek View Post
    The washer was probably glued onto the end of the carrier tube to overcome either a short ground tube or a too-long cocking tube placement.

    It sucks that you got stuck with someone else's experiment unknowingly. Unless I'm mistaken it appears that you got a cast stainless receiver there so it will be worth your time to determine the problem. Cast models are not known for misplaced cocking tubes so it might just need a new carrier.

    If you are willing to take some measurements we can get this sorted out. Ideally I'd like to know the length of the carrier tube, length of the bolt head, and the bolt gap with the cocking handle support removed. Eventually I'll want pics of the locking piece shoulders and the front edge of the bolt head windows, but it might not come to that.
    O.P- THIS ^^^^ is a guy who can get ya straightened out!!

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    Hi guys, so I measured the following:

    *Bolt carrier length of 275 mm or 10.827"
    *Bolt head length is 46.03 mm or 1.812"

    Pics of the following: Bolt & Carrier outside of gun with bolt locked up (bolt gap gauge is at .06mm or .0026"), 2 angles of the bolt and locking piece.

    Cetme issue 2.jpg
    Cetme issue 3.jpg
    Cetme issue 4.jpg


    Thanks for any help you can provide!

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    Senior Veteran SgtHorvak's Avatar
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    Quote Originally Posted by ryukikass View Post
    Hi guys, so I measured the following:

    *Bolt carrier length of 275 mm or 10.827"
    *Bolt head length is 46.03 mm or 1.812"

    Pics of the following: Bolt & Carrier outside of gun with bolt locked up (bolt gap gauge is at .06mm or .0026"), 2 angles of the bolt and locking piece.

    Cetme issue 2.jpg
    Cetme issue 3.jpg
    Cetme issue 4.jpg


    Thanks for any help you can provide!
    If you're sure that you have an accurate measurement of the carrier and bolt head, it seems to me that your bolt head is too short, as I believe it should measure closer to 1.835-ish". Your carrier arm may be a tad short as well, as I have read that it should measure around 277mm, or about 10.9-ish". I have a source that says a new, in-spec carrier will measure 10 15/16", or about 10.9375". Again, I am not the expert that Holescreek and others are here, but I would guess that short carrier arm is possibly contributing to your excessive cocking tube gap. Of greater concern, I think, is that your bolt head seems as if it may have been ground. And I don't THINK that a bolt gap measurement outside of the barrel/trunnion assembly is extremely valid. Greater knowledge and experience than mine will be along shortly, I am sure!

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    holescreek's Avatar
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    I found this quote from Bladeworks123: "The spec overall length of a new un-altered CETME bolt carrier, the distance from the front of the recoil spring guide barrel, which contacts the cocking handle support to the rear of the carrier assembly is 277 mm or 10 15/16" (10.9375").

    I also found a post of my own where I measured 2 Cetme carriers and got 10.930" and 10.89". And the standard length of a Cetme bolt head is 1.832", yours is definitely ground.
    The bolt gap must be measured inside the receiver with the cocking handle support removed. Feeler gauge goes in through the mag well.

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    Thx guys, coincidentally Apex has the parts kit available. I'll measure/try those when it gets in later this week.

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    The bolt gap must be measured inside the receiver with the cocking handle support removed so that the carrier can't rest on the support and give an artificial gap. It also has to be locked into the trunnion with the rollers extended to contact in order to establish whether the barrel has shifted forward in the trunnion. In your case with the bolt head ground down you must have a minimum bolt gap of .016" for the barrel to be in the correct position.

    Don't expect much from the Apex kit, the last few I've seen were bottom of the barrel kits. But for the $99 price they were advertising I was just barely able to pass one up. I keep telling myself I'm through with Cetmes.

  10. #10
    Senior Veteran SgtHorvak's Avatar
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    "Don't expect much from the Apex kit, the last few I've seen were bottom of the barrel kits. But for the $99 price they were advertising I was just barely able to pass one up. I keep telling myself I'm through with Cetmes"
    Aw, C'mon, Dude!! We all know better!! At $99, I bet you can come up with SOMETHING untried yet!! I saw your CETME bullpup, after all!! I bought an Apex kit at $124 last fall while I was getting your help with my SARCO kit build, and I thought $124 was too good to pass up!! The steel parts in my Apex kit all look pretty decent, although the wood wasn't as nice as the SARCO kit that is up and running.
    OP...don't get discouraged!! Once you get that rifle sorted out and running well, you'll think it was all worth it!! I LOVE mine, and I have great pride in it...as you will in yours, too!!

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