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I started a build a few weeks ago after receiving a Cetme C parts kit. After more research, I recognized I wanted the G3 furniture on it, so I picked up a set, along with a receiver, and other various parts. My barrel is back ordered, but hopefully will be arriving soon, which brings me to my first question.
I've read quite a bit of info on pressing the barrel, but I've not seen any info on how far it needs to go in the trunnion. I see people mention that if you go to far, you have to press it through and start over, but how to you know where to stop?

My second question is on the G3 cocking spring and cetme bolt carrier. I'm supposed to sand down the nylon bushing on the cocking spring, so that it fits into the cetme carrier. What I haven't found is how much do you sand it down and how far is it supposed to go into the top of the carrier.

Any help would be appreciated so I can work on this over the weekend.

Thank you!
 

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I'm no expert by any means - but here's how I pressed my MP5K barrel.

I pressed barrel into trunion well past the valley for the rollers to lock. Then keep checking where the rollers are seated in the valley (using the BCG of course). Too high in the valley = not close enough. Too low in the valley = too far. Rollers in the middle = whip out the feeler gauges and start checking bolt gap! It wasn't really that hard, just very time consuming. Of course, I defer to the experts for an easier way, but I got my bolt gap to .018 with a little effort.

Never built a CETME so I have no idea about the cocking spring - sorry :(
 

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Instead of sanding, drive out the roll spring on the ends of the cetme recoil rod and the HK one and install the cetme end and guide on the HK and you are good to go.

The end of the rod must be able to past through the carrier


EDIT: On another note, look at your barrel pin hole through the reciever and note it does not line up with your pin. You will want to file the rear edge so yoh can access the pin should you need to do any bareel work after it is done
 

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Just press the barrel into the trunion, take your BCG with the bolt locking mechanism removed (thats the thing that holds it in the unlocked position) and try and get the barrel breech face to line up to the back inside face of the trunnion. Slide the BCG in and put some pressure on the back, making sure that it is as square as possible (it will kind of wobble around when locked, just visually align it to the barrel/trunnion). Now take a feeler gauge and measure between the back of the bolt head and the front of the carrier.

If you find zero gap, you went too far and just press the barrel all the way through and start over. It can be a gamble, once I got lucky and got it in 1 pass and others I needed 8 times to get it right.

Ah, also before I forget it's always a good idea to use a bit of anti-seaze or grease, just a little. After your confident of the bolt gap you drill your pin hole and press it in to lock it in place.
 
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