Cetme C barrel broke out of trunnion after 150 rounds!

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Puddinhead

Puddinhead

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My son and I were shooting his Cetme C that was put together by a shop in Virginia at our range today. He got the parts kit from Apex and sent them to the gunsmith that put it together for $400. While shooting today we experienced 2 rounds in a row that didn't fire. The ejected rounds had no primer mark at all on them. Also the charging handle was getting jammed up at the back of the stroke. Not quite sure what was going on we headed home after firing about 50 rounds.

When we got home we noticed a ring of unpainted metal behind the front sight. It was freshly painted when it was put together and the stripe at the sight was a red flag. We still couldn't get the charging handle to operate smoothly either. We got the lower hand guard off and found the 2 weld spots where the barrel is pressed into the trunnion had broken and the barrel was forward about 1/8". Actually it looks like the trunnion itself broke at the welds, and furthermore the trunnion looks as though it's cast, not machined. I don't know if the trunnion was the one that came in the Apex kit or one that was supplied by the gunsmith. I assume the pin is broken as well. This just seems really bizarre given the few shots through the rifle! I don't know if it's shoddy work by the gunsmith, a shoddy trunnion, or something else.

The first 100 rounds we had shot before were Tulammo and today I used 175gr reloads using light loads using H335 and IMR4895. I was a grain over the low side so the loads were definitely not heavy.

I would appreciate anyone's input on this. Also any thoughts on whether the charging handle jamming up is due to the barrel problem. My son is calling to talk with the guy who built it tomorrow. I will let you know what he says. Thanks in advance.

Jon
 
Um,....wow. the charging handle issue is definitely related to the barrel coming out of the trunnion, and sliding forward. Probably canted too. Something is wrong with that weld. And the trunnion too. Gunsmith rebuild time.
 
According to Small Arms of the World 9th edition. "The Spanish CETME uses a special 7.62 Nato round load which gives lower pressure than those encountered with Nato cartridges loaded by other countries." While it can fire other Nato rounds, your heavy bullets may have over stressed the design. The cast trunnion may have contributed to the failure.
 
No, the bullets didn’t “stress the system.” I had a Century Cetme many years ago, and fired probably a few thousand rounds with no worse for wear to to it!

Looking at it, I’m wondering if it even has a barrel in installed! Can you SEE the pin? I’m wondering if they just relied on the weld.. I’ve never seen one welded there! Ya don’t weld the barrel to the trunnion! Side note: it’s not a machined part. Those are investment “cast” parts. Easy to tell by the grain structure of the steel. Looks like sand almost… that’s cast. Regardless. Take it back to the builder. I think your “gunsmiff” took some shortcuts in the build. Ashame. But happening more & more. They can fix it or give your money back! Remember: it’s the SQUEAKIEST wheel which GETS the the oil!
 
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Zygodactyl said:
According to Small Arms of the World 9th edition. "The Spanish CETME uses a special 7.62 Nato round load which gives lower pressure than those encountered with Nato cartridges loaded by other countries." While it can fire other Nato rounds, your heavy bullets may have over stressed the design. The cast trunnion may have contributed to the failure.
Click to expand...

This was true of the Modelo B, but the Modelo C was engineered to handle standard NATO pressures.

The development story is in the Collector Grade book Full Circle (out of print now and crazy expensive).
Full Circle.jpg
https://www.amazon.com/Full-Circle-Treatise-Roller-Locking/dp/0889354006

The cast trunnion or barrel shank seem the most likely culprits.
 
Again, I’m thinking they shortcut and welded the barrel to the trunnion. I’ve never seen one welded there. It shouldn’t be! And I don’t see the head of a barrel pin either. Is the barrel pin even there?? Can’t break one of the stock barrel pins! Unless they used a piece of CHINESIUM, or cast Aluminum..
 
Puddinhead said:
Here are a couple of pictures showing the broken trunnion. . .
Click to expand...
I am solidly in the "grinders and paint make me the welder I ain't" category, but your gunsmith can't weld at all.

There are good reasons we don't weld barrels to receivers, but that's not really welded at all. He may as well have JB Weld'ed it for all the penetration he got.
 
edwardware said:
I am solidly in the "grinders and paint make me the welder I ain't" category, but your gunsmith can't weld at all.

There are good reasons we don't weld barrels to receivers, but that's not really welded at all. He may as well have JB Weld'ed it for all the penetration he got.
Click to expand...

I agree that he isn't a welder at all. I'm long retired but carried an ASME Code 9-G 6 test card for many years to prove I knew what I was doing and I haven forgotten.
 
From looking at the photos, the trunnion did NOT break. What you are seeing is a lack of penetration during the welding process and the welds themselves have failed. I agree with everyone else, the gunsmith did not get proper penetration when he welded it. I also would be looking for a different gunsmith.
 
Ok, some people commenting that DON’T KNOW, shouldn’t. It just muddies the water. Talking about the condition of the welding is moot! It should not have been welded there… PERIOD! Barrels do NOT EVER get welded to the trunnion. The barrel is pressed in and pinned. That’s it. Welding is typically a “cover up”. Either the pin hole was drilled too large, or perhaps that is only a fake through in. I don’t don’t know. But stock barrel pins do not break. They are incredibly strong.
 
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I think the "smith" you took it to does not know how to build G3's and Cetme's. Did this guy make big claims about being some master builder?
 
Bcwitt said:
That is supposed to be pinned, not welded. I cannot believe some idiot did that.
Click to expand...


There’s only a relatively short list of smiths that can do G3 and Cetme builds. I wish Arizona Response Systems did these builds. He’s worked magic over the years with the usual trash FALs being assembled here in the US.
 
It appears the barrel journal was destroyed by being pressed through the trunnion too many times and the builder tried to salvage it by knurling the OD before pressing it. This is an acceptable fix if done correctly, but it wasn't. They didn't turn the barrel back down to the correct size after knurling which greatly reduced the surface area contact with the trunnion. Then they tried to pin the barrel and found out that it wobbled because of reduced contact area and then tried to weld the barrel to the trunnion in an effort to stop the movement. After a couple of shots the weld broke and the barrel got jack hammered forward until the FP could no longer reach the primers.
I sincerely hope that this wasn't a real gunsmith but rather some pretend builder. Your barrel might still be salvageable, but you didn't buy a "salvage" barrel to begin with. Based on the pics the whole build is questionable and more than likely your cocking tube gap is **** too. There are no cast trunnions, just really bad welds.
 
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