Is this normal?

[Brian O]

I have noticed that oftne when cock my CETME that the bolt head does not lock into place as in the following picture:
Is this normal? if not what needs to be done to repair it?
If I tap the but of the rifle on the floor or dry fire it it snaps shut.

[Nazgul]

Mine would do that too. Grease that bolt and locking piece up and hand cycle it about 100 times. Clean off the grease(or not) and then see if it does it.

[Brian O]

cool, thanks!

[Bluedog]

I have noticed that oftne when cock my CETME that the bolt head does not lock into place as in the following picture:
Is this normal? if not what needs to be done to repair it?
If I tap the but of the rifle on the floor or dry fire it it snaps shut.

Let it slam forward full force. If you ride the carrier forward it will not lock.

[Brian O]

yes I have been letting it go from the full cocked position and it still does it. thanks though

[Bluedog]

yes I have been letting it go from the full cocked position and it still does it. thanks though

Then no, it's not normal.

I'd start by checking for signs of the bolt carrier rubbing on the receiver.

Also, you can generally smooth out the action of a century built Cetme by detail stripping it and giving it a good bath in hot soapy water, using Dawn dish detergent and a baby bottle brush to scrub the inside of the receiver.

The Dawn will degrease it and you will be surprised how much grit you find in there. I did this to a Friend's Cetme, and was so impressed with how the action smoothed out that I tried it on mine as well. Even after several years of owning and meticulously cleaning it, it still came remarkably clean and is now much smoother.

[hunter_la5]

Also, check the recoil rod to make sure it's not bent/binding on the carrier.

[bladeworks123]

Also, look at the rails inside the receiver just to the rear of where they meet with the trunnion. See if you see any sign of the rollers impacting the rails. Given the distance shown in your photo, it indicates that perhaps the bolt head is hitting the trunnion and prematurely starting to set the rollers.

[Brian O]

thanks for the help I will look into it and get back

[Brian O]

Also, check the recoil rod to make sure it's not bent/binding on the carrier.

what is the best method of checking it for straight?

[Brian O]

It was the bolthead hitting the trunnion. When I examined the trunnion I noticed a little tiny scrape mark on the top side of the trunnion which turned out to be from the roll pin in the top of the bolthead.

The pin was sticking up just a little bit maybe .020 or .030 at the most. tapped it back down with a flat faced hammer and one of the pins that holds the buttstock on the rifle. The action now cycles properly.

Thanks all!

[hunter_la5]

Glad to hear it was something simple. :)


what is the best method of checking it for straight?

This is probably no longer relevant, but for future reference, you can usually just eyeball it. If you're still not convinced, just hold it against something flat like your kitchen table or a straightedge. It should be at a roughly 90 degree angle from the buffer, and with no discernible bends in the rod. Doesn't really have to be too precise, just make sure its not obviously slanting left/right or up/down or bent.

[Brian O]

cool thanks for the info

[bladeworks123]

Glad to hear it was something simple. :)



This is probably no longer relevant, but for future reference, you can usually just eyeball it. If you're still not convinced, just hold it against something flat like your kitchen table or a straightedge. It should be at a roughly 90 degree angle from the buffer, and with no discernible bends in the rod. Doesn't really have to be too precise, just make sure its not obviously slanting left/right or up/down or bent.


You can also pull your bolt carrier and then install the buttstock back on the rifle, look in the ejection port and see if the spring and guide are generally centered in the upper portion of the receiver, and make small adjustments to get it as close as possible. Good to hear it was just the roll pin, good job!!

[Brian O]

just out of curiosity what are other possible causes for the bolt hitting the trunnion?

[bladeworks123]

If the trunnion was not installed level or square to the rails, in other words if it is cocked a little one way or the other, the bolt head will impact the trunnion and try to twist it's way into the trunnion. That is enough to cause the bolt head to push back and set the rollers.

If the receiver rails were not close enough together when the trunnion was welded in, the bolt head can hit one side or the other of the trunnion and try to set the rollers, causing the "dimples in your rails" syndrome.

A receiver that is bent or bowed to one side or the other, either left or right. Causes the bolt head to hit one side of the trunnion or the other. Takes a lot of craziness for this one to happen. But I have seen bent MP5's that this happened to.

The roller pin sticking up like you already found, and dragging on the top of the trunnion.

If the receiver was built from a bent flat, the top half of the reciever can be too short and that will cause the bolt head to drag on the top of the trunnion. This is pretty unusual, but possible if the receiver is pressed in too deep around the charging tube portion.

A lot of powder residue built up around the area where the rails meet the trunnion can cause enough drag to try and set the bolt head. But you would have other "dirty gun" problems as well, usually long before this happens.

Magazine set way too high. You would also experience failure to feed problems with this one, especially on the last round, and the rifle would be noticeably hard to charge with a full magazine.

That's about all the reasons I can think of at the current moment....