Cetme C barrel broke out of trunnion after 150 rounds!

[Carl N. Brown]

The Spanish issue ammo for the CETME was downloaded for control of the gun when fired full auto.

Same reason as the 6.5 Arisaka rounds for their squad level light machine gun were lower power than the rifle issue 6.5 Ariska.

Not because the select fire guns were too fragile, but because downloaded ammo made them more controllable under full auto.

 

[Insignificant bill]

I would think properly pressing the barrel and installing the pin would be the proper way to do it. But then I see other people talking about welding it. Is there a difference in the trunnions used?

 

[Holescreek]

The barrel is never welded into the trunnion on any Cetme/HK build. Barrels are pressed and pinned then the trunnion is welded into the receiver. In a dozen years of building these guns I've only ever seen one home gunsmith welded a barrel to a trunnion.

 

[arsterling180]

I would think properly pressing the barrel and installing the pin would be the proper way to do it. But then I see other people talking about welding it. Is there a difference in the trunnions used?

No. It’s ignorance of how G3s and Cetmes are built.

 

[Bcwitt]

Come to think of it, ive never seen one knurled before.

 

[BigBlue 94]

Come to think of it, ive never seen one knurled before.

Ive only seen one cetme, my CAI C308. And couldnt say if it was knurled or not. But i did think to myself that it looked out of place. I even went as far as to critique the knurl itself: its not the worst ive seen. My first couple tries were, uh, pretty poor...

 

[Bcwitt]

Ive only seen one cetme, my CAI C308. And couldnt say if it was knurled or not. But i did think to myself that it looked out of place. I even went as far as to critique the knurl itself: its not the worst ive seen. My first couple tries were, uh, pretty poor...

I had that same rifle. Was a decent shooter.

 

[BigBlue 94]

I had that same rifle. Was a decent shooter.

Mine runs great! Just needs to be well oiled. I just put a set of refinished surplus wood furniture on in place of the plastic.

 

[GBExpat]

I bought one, each, of the original Century CETME C S/A Variant rifles w/cast s/s receiver (Nov'01) and the next edition with stamped steel rcvr (Jul'02).

I have always found both to be reliable and accurate.

The cast s/s rcvr rifle is very well done while the stamped-rvcr version is a sloppy copy. O'course the former cost me 50% more than the latter.

The stamped-rcvr rifle did require beaucoup cleaning and a modicum of tweaking on my part, but it came to me NIB from Century, so it matched my expectations.

 

[MachIVshooter]

first you can't weld high carbon steel to cast. It can be brazed or soldered.

Sure you can, but you need to use a stainless filler. Standard copper coated carbon steel wire won't bond well.

I've repaired quite a few sand cast top break revolver frames with 321 wire using the TIG.

 

[Saguy46]

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.

Could you share that list? I have a Cetme C parts kit that I would like built. I reached out to one well-regarded HK builder who said they didn't do Cetme model C, which I find odd. He explained that HK made over 200 revisions on the G3.
Anyway, any recommendations are appreciated.

 

[tark]

Same reason as the 6.5 Arisaka rounds for their squad level light machine gun were lower power than the rifle issue 6.5 Ariska.

I have never heard of this. Can you give a source?

 

[Jim Watson]

Same reason as the 6.5 Arisaka rounds for their squad level light machine gun were lower power than the rifle issue 6.5 Ariska.

Author of the Wiki says 6.5x50SR G ammunition was loaded with double base powder at lower velocity to reduce muzzle flash from the short barrel of the weird Type 11 machine gun. Nobody I can Google will say whether it went into standard issue for rifles, too.
Japanese ammo logistics must have been awful. They started out with 6.5mm rifles and LMGs and a 7.7mm HMG. They decided they needed more rifle power against angry Chinese so they adopted a 7.7mm rifle round different from the MG ammo. Then MGs for the rifle round. And light load LMG 6.5 on top of all that mess. And let's don't forget the IJN with real .303 British Lewis guns.

 

[Carl N. Brown]

Jim Watson: ".... And let's don't forget the IJN with real .303 British Lewis guns."

That ammo was listed by IJN as a 7.7mm rimmed.

I think unnecessary ammo supply complications in the WWII Japanese and Italian militaries ought to be a lesson.

 

[JDGray]

A good gunsmith, does not have to tell you how good he is... Sorry you did not get a good one.

 

[doubleh]

I know absolutely nothing about the gun but the weld in the second picture failed in the HAZ and considering the thinness of the part that failed I can understand why even if it wasn't cast. I would be knocking on the door of the person that did that.

 

[Rshooter]

I am not a welder but am a NASA certified solderer. That weld looks like what we used to call a glob job.

 

[jmorris]

I am not a welder but am a NASA certified solderer. That weld looks like what we used to call a glob job.

Yeah, it seems that one is lucky if the parts are correctly oriented before they pull the trigger. I had a century built one I had to cut apart to correctly align the parts and reweld.

 

[4v50 Gary]

I'm against welding on the barrel. Too much heat and you compromise the metallurgy. Besides, that's a very bad weld.

 

[lysanderxiii]

The trunnion is supposed to be plug welded to the sheet metal receiver.

The barrel is supposed to be a 0.002" interference fit with the trunnion, and pinned in place.

 

[12Bravo20]

The trunnion is supposed to be plug welded to the sheet metal receiver.

The barrel is supposed to be a 0.002" interference fit with the trunnion, and pinned in place.

Then the said gunsmith messed not once but twice by not properly installing the barrel and a bad weld job.

Either way I would find a better smith to fix it.

 

[BreechFace]

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..

I agree, the barrel should not be welded to the trunnion.

This!

 

[Ignition Override]

Wow. What a mess!

The potential for such amateur work, or Any work which causes any problem…

…explains —Exactly— why my recent semi-auto rifles were purchased new-in-box , via Buy Now. The first such were the VZ-58 and ZPAP.
Then a pair of HK-91 clones: PTR-91 (A3SK) and the “classic GI” version.

I never wanted any kit , needing an experienced pro.

My condolences to the OP.