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PostPosted: Fri Sep 19, 2008 4:25 pm 
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Couple questions for those experienced CETME owners. I took mine out today (now that I've replaced the ground bolt-head with a new one and changed the locking piece). After about 6 rounds, the rifle began failing to eject. First 6 were fine then after that a couple here or there, then by the end of 20 rounds that last 8-10 wouldn't eject at all. I was shooting South African NATO ammo. Could it be the flutes were getting dirty causing it to not eject the case. It fed fine during shooting BTW.

Second question, I thought I recalled something about the CETME needing to very clean, or it could have been, the CETME needed to oiled very well for it function good. Anyone have input on that too?

Thanks.


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PostPosted: Fri Sep 19, 2008 4:51 pm 
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One or two drops of oil on the bolt rollers, a little oil on the recoil spring, and a couple of drops on the bolt guides in the receiver is all that is necessary. The chamber should be dry. The flutes allow the gasses from firing to float the brass free as the bolt begins to move back. You may have crud in the chamber, making it "sticky." You can clean with solvent and a .38 or .40 cal bore brush.

For the failure to eject, is the brass leaving the chamber, or is it getting stuck? As far as I know, if it sticks the bolt would likely rip the case head off, because these guns are powerful extractors. If the brass is leaving the chamber and getting hung in the receiver, check the fit of the ejector in the bolt head. The ejector, which see-saw's up and down as the bolt is cycled, has been known to get bent, caught, or not go high enough if the pistol grip shelf is too low. Brass from the CETME should normally achieve a low earth orbit after exiting the weapon. :lol:

Let me know about where the brass is hanging, and we'll go from there.

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PostPosted: Fri Sep 19, 2008 6:04 pm 
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The brass stays in the chamber (it does not stove pipe or anything). But, it does come out when I manually pull the handle back and manually eject the brass. I'm gonna' go outside and try some other ammo for the heck of it.

.....

Ok, back from shooting 3 rounds of Federal Premium White Box 7.62.51 (NATO spec). All three rounds ejected. However, after firing the bullet 2 of the 3 rounds kind of flopped out of the receiver and fell within a foot or two from me. The other shot flew like it should, about 15 feet away. Weird. I'm gonna' clean it and fire 3 more rounds of Federal and see how it acts, and then 3 rounds of South African.

.............

It's definately something to do with the ammo. I fired 2 rounds of South African and it didn't eject. I fired 2 rounds of Federal Premium White Box and it ejected each time. Another thing, the brass from the Federal comes out pretty warm to the touch. The SA is not warm at all. I also noticed more muzzle flash from the Federal. Could the SA ammo not be hot enough to cycle the action reliably? Anyone?


Last edited by Black Wolf on Fri Sep 19, 2008 8:50 pm, edited 1 time in total.

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PostPosted: Fri Sep 19, 2008 7:37 pm 
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My G3 functions great with the SA ammo. Or with any other for that matter. I have a case of S&B Nato spec, too, and that seems a bit hotter but the rifle just eats anything I put into it.

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PostPosted: Fri Sep 19, 2008 10:39 pm 
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That doesn't leave many options. If it functioned normally before replacing the bolt head and locking piece, you may have the wrong locking piece. HK and CETME locking pieces look very similar, but the angles and curves are different.
Or you may have run out of bolt gap. Did you double check it after replacing the bolt head? Century ground bolt heads to falsely raise the bolt gap on kit guns that never had the barrels properly reset. It's like the gun is remaining locked during firing. The roller locks are a tuned balance of forces, and it wouldn't take much to upset them - causing overly forceful extraction at one extreme, or limted/ nonexistant extraction at the other. The brass falling a few feet away is a dead giveaway that energy is being consumed somewhere else. CETME brass should be thrown at least 20 feet or so. My guess is that too little bolt gap is keeping the action locked during firing. It sounds like there just isn't quite enough energy to push those rollers up the ramp because of where they're resting.

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"Oh bother" said Pooh as he chambered another round...

A computer beat me at chess once, but close range handguns was another story...


Last edited by cheggie on Fri Sep 19, 2008 10:44 pm, edited 1 time in total.

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PostPosted: Fri Sep 19, 2008 10:41 pm 
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You replaced the bolt...did you check your bolt gap?

Should be between .008 and .016 for optimum perfomance.

The way I have heard is that less bolt gap will make it take more pressure and time for the bolt to unlock, and too much...it will unlock to fast becuase it may not be fully locked.

Check to make sure your recoil spring guide rod is straight, and clean the chamber well :thumb: .

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PostPosted: Sat Sep 20, 2008 8:57 am 
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Yup. Cleaned it good - flutes too.

Bolt gap with the new bolt head and locking piece is .011", in fact, I switched out the old locking piece and new locking piece and got the same measure of .011"


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PostPosted: Sat Sep 20, 2008 9:45 am 
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Did you try shooting it with the original locking piece & new bolt head yet? I'm interested to know what happens... :thumb:

Also, double check that the ejector didn't get bent and is riding on the bottom of the bolt. It should slide cleanly into that slot in the bolt head. If they get bent it isn't always clear, but that could be holding it up.

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"Oh bother" said Pooh as he chambered another round...

A computer beat me at chess once, but close range handguns was another story...


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PostPosted: Sat Sep 20, 2008 11:00 am 
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Yup. Just tried it with the old locking piece and the new bolt head. I even put the old rollers back in which were the same size as the new ones. Sometimes it ejects the South African (S/A) and sometimes it doesn't. It seems it may be getting a little better (or maybe I'm dreaming), but yesterday at the range the last 12 out of 20 shots didn't eject at all, and no stove pipes. I shot 10 rounds today, 5 ejected completely, 2 stove pipes, and 3 where it looked like the bolt came back about an inch but didn't eject the casing (this didn't happen at all yesterday). All S/A ammo.

So far I've tried every combination of the old parts with the new bolt head. Currently put it back with old rollers and new bolt and new locking piece. Could the bolt head be dragging somewhere I wonder or need broken in? Bolt gap is .011" so I should be good on that.
........
Update:
Ok, I'm getting Peed off. Just went out and tried 3 rounds of the Federal and none of the ejected. The extractor is grabbing the brass and pulling it back, because I can see the brass still in the extractor as I ride the bolt back. Doubt it's the ejector too - when I manually pull the bolt back it ejects the empty casing everytime - and, it worked good prior to changing to the new bolt head. I can see the ejector hitting the case head and popping it out. I just don't think the bolt carrier is coming all the way back with the new bolt head for some reason.

I think my next test is to put the old ground bolt head back and old locking piece back together and try it with that configuration. It seemed to function better last time I shot it that way.

..........
Another Update:
Put in all the old parts (ground bolt head, old locking piece, old rollers) and fired about 10 rounds. Both S/A and Federal NATO and all fired without problems, except one Federal round didn't eject all the way. It seemed that the rounds started out sluggish as far as ejecting, going about 5 feet at first, but by the 10th round they're flying about 15 feet away.

Now what.


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PostPosted: Sat Sep 20, 2008 12:52 pm 
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Hmm, were the rollers tight in the new bolt head?

Try working the action 100 times with the new parts, .011 should be good to go.

Maybe the new parts need broken in.

Also just for the heck of it, if you could take a picture of your bolt head with the action open and the extractor just coming through the bolt.

If you still cannot figure it out, visit www.militaryfirearm.com.

It is the old CETMErifles.com.

GL

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PostPosted: Sat Sep 20, 2008 2:53 pm 
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New rollers tight in bolt head: They're more tight than the old bolt head. They rattle in and out if you shake the bolt head, which is normal, but they're is definitely less play in them compared to the old bolt head. I figure that's normal since that is likely the part that was worn on the old bolt head.

As far as pics, I hate to take the old bolt head and reassemble the new one again for a photo. I've looked at the new bolt head and how the extractor syncs with it pretty close and it operates and looks just like the old bolt head. It ejects manually just fine, pulling the charging handle to the rear. I really don't think it's an ejector issue because when it fails to eject the bolt isn't going all the way back. What I'm saying is, it never gets to the ejector when it fails. Also, it would seem that it would likely fail with the old bolt head as well if it were an ejector issue. Just my thinking.

I'll check out the link you provided - maybe they can help.

I've thought about measuring all the sides of the new and old bolt head and compare to see if maybe the new one is larger somewhere and causing some drag.


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PostPosted: Sat Sep 20, 2008 7:37 pm 
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There are two more things I can think of that would cause the bolt to drag. Check the recoil rod to make sure it isn't bent, and check the stamped guide rails inside the receiver where they meet the trunnion. Where the stamped metal guide meets the forged trunnion, the transition should be near perfectly smooth. I have seen Century guns where the guides were misaligned. The trunnion is welded the the receiver above and below the guides, but it is possible to persuade them into alignment if they've shifted. Break the gun down, and with the bolt removed view and feel the transition from guides to trunnion. Also, try pushing the bolt home by hand through the trigger housing opening. You should encounter little to no resistance until the rollers pop out. Remember, this gun's action is like a physics tug of war. There is enough energy created when fired to cycle the action, it's just getting used up somewhere it isn't supposed to. There is no break in, it either will work right or not.
How far is Pilot Mountain from Laurens? If I could see this thing I know I can fix it. I had one, and I had to fix several bugaboos with it.

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"Oh bother" said Pooh as he chambered another round...

A computer beat me at chess once, but close range handguns was another story...


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PostPosted: Sat Sep 20, 2008 9:31 pm 
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Here's some pics of the recoil rod and the rails/trunnion connection. I don't see anything out of the ordinary (but I don't have another CETME to compare it to either). Note the wear mark at the center of the trunnion in the last picture - I wonder if it's dragging there. Does yours have a wear mark there?

You are about 3 hrs from me. I go to Greenville SC regularly. If we can't get it working this way, I can possibly come down next weekend to work on it.

Image
Image
Image
Image


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PostPosted: Sat Sep 20, 2008 10:42 pm 
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Just got mine out of the crate and check, everything looks the same as yours. Same wear mark, and same thing where the trunnion and rails meet.

I say check that link I gave you, hopefuly you already registered becuase it may take a few days to get approved.

How much recoil does your rifle have? Maybe your rifle will run better with more gap? Maybe it will run better with less gap?

Is .011 the most amount of gap you can get with the new parts?

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PostPosted: Sun Sep 21, 2008 5:35 am 
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Yugom5966 wrote:
Just got mine out of the crate and check, everything looks the same as yours. Same wear mark, and same thing where the trunnion and rails meet.

I say check that link I gave you, hopefuly you already registered becuase it may take a few days to get approved.

How much recoil does your rifle have? Maybe your rifle will run better with more gap? Maybe it will run better with less gap?

Is .011 the most amount of gap you can get with the new parts?


Thanks for the help Yugo - I appreciate you checking for me.

Yeah, registered last night. Hopefully it'll activate soon. I can't post anything yet.

Recoil is modest with the new parts - even when it doesn't hiccup. Definitely a little more recoil with the old parts. Yes, .011 is the best I get. I get the same thing whether I use the old rollers or new, and the old locking piece or new, nothing changes the gap there. The only the thing changes the gap is the new bolt head - I put in the new bolt head, the old rollers and old locking piece and got .011 - and the same for all the new parts. Apparently the only real worn part was the bolt head. I guess I now have some spare rollers and locking piece for the future.

...... Update.....
I decided to put the new bolt head attached to the bolt carrier but without the rollers to see if I could feel it binding anywhere. It's as smooth as a glass sliding in and out. Therefore, I suspect it has to do with the tightness of the rollers in the bolt head. Just a thought.

Here's a couple of photos of the bolts heads, having pulled the charging handle just enough to break open the space shown between the bolt head and bolt carrier.

New Bolt Head:
Image
Old Bolt Head:
Image


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