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hywayflyr
01-30-2013, 03:35 PM
Need some help here, need to remove the barrel from a CAI cast ss receiver. Has anyone uncovered the barrel pin and pressed it and the barrel out or do you have to remove the trunnion from the receiver? Any help would be greatly appreciated.

7.62guy
01-30-2013, 06:47 PM
Welcome to the forum. Some of the group that are really good with the cetme will chime in here soon to help you. I do know that the barrel is pressed in and out. Hope that helps a little.

bladeworks123
01-30-2013, 10:01 PM
You will need to uncover the pin and press it out, then press the barrel from the rear. There is really no good way to de-mill a trunnion from a cast receiver without ruining it. Then welding the trunnion back in makes the third time it was welded on and they can get soft on you from being welded too many times. You would also have to demill and remove the cocking tube. Also, extra caution needs to be used when you are pressing the barrel out to keep from cracking the front of the receiver. What I use is an old bearing race that is a little smaller than the trunnion to support against just the trunnion. Somewhere I have the dimensions of where the pin sets on a stainless receiver,,, I will look for it. You start with drilling a 1/8 inch pilot hole and slowly enlarging it with a dremel until you find exactly where the pin recess for the trunnion is, once you find one edge of it, you can follow it around with a dremmel and fluted cutter to open it up. Also to be sure,,,, is this a cast CETME and not a cast Hk platform? The reason I want to be sure is that the pins are located in different positions.

hywayflyr
02-01-2013, 03:18 PM
7.62guy, thanks for the welcome. Bladeworks123 this is a cast cetme, has the cetme paddle wheel rear sight. I have uncovered barrel pins in the stamped cetme receivers before, but there are some unusual things going on with this rifle. First, the barrel appears to have been welded to the front of the trunnion, and that weld is cracked. Second, using the dimensions I have used on stamped receivers, I am unable to locate the barrel pin. It almost seems that the receiver was cast around the trunnion, but there is evidence that the trunnion was also welded to the receiver. I have to admit, given CAI's reputation, that I don't think they would have the capability to weld a hardened steel trunnion to a cast stainless receiver. Right now the plan is to visit a friend with a mill this weekend and do some exploratory machining using a cetme trunnion as a guide. He suggested that the receiver was cast around the barreled trunnion and only then did they realize they forgot the barrel pin, hence the welded barrel.

bladeworks123
02-01-2013, 05:31 PM
7.62guy, thanks for the welcome. Bladeworks123 this is a cast cetme, has the cetme paddle wheel rear sight. I have uncovered barrel pins in the stamped cetme receivers before, but there are some unusual things going on with this rifle. First, the barrel appears to have been welded to the front of the trunnion, and that weld is cracked. Second, using the dimensions I have used on stamped receivers, I am unable to locate the barrel pin. It almost seems that the receiver was cast around the trunnion, but there is evidence that the trunnion was also welded to the receiver. I have to admit, given CAI's reputation, that I don't think they would have the capability to weld a hardened steel trunnion to a cast stainless receiver. Right now the plan is to visit a friend with a mill this weekend and do some exploratory machining using a cetme trunnion as a guide. He suggested that the receiver was cast around the barreled trunnion and only then did they realize they forgot the barrel pin, hence the welded barrel.

The receiver and trunnion were not cast together. Century liked to weld the trunnion to the receiver around the circumferance of the forward edge of the trunnion. My guess would be that if you can't locate the pin, they may have used an Hk platform trunnion. The pin sets in a diferent position. There is a thread here on the site that gives you those differences, I am ony my droid at the moment away from my shop. When I get back there I will look up the two different measurements for you. The barrel being welded to the trunnion by Century would be a new one on me...they have done some crazy stuff but.....anyway, would like to see a picture of that one.

bladeworks123
02-01-2013, 05:37 PM
In addition, welding the cast stainless to the trunnion is done all the time. There is no incompaibilty issues with that if it's tig welded with stainless filler rod. Same thing is done when welding cocking tube, rear sight.

bladeworks123
02-01-2013, 09:34 PM
CETME barrel pin c/l is 10mm horizontal from the front of the trunnion. Hk pin is 8mm c/l from the front of the trunnion. Both barrel pins are located in the same spot vertically. You should be able to get on top of the pin if you are at 9mm. If they welded the trunnion in the same way every one I've ever seen is done, there is probably about 1mm added to the length of the trunnion in the front caused by the weld. And I also verified that 10mm measurement on another cast stainless CAI CETME receiver that is not blind pinned. On that receiver the center line of the barrel pin is located 12.5mm up from the bottom of the receiver. On a bare trunnion the center of the pin is 11mm up from the bottom.

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hywayflyr
02-02-2013, 06:59 PM
OK, I finally found the pin hole on the left side of the receiver. My drill location was fairly close when I tried from the right side, however the trunnion pin hole on the right side was welded closed. The barrel pin was pressed only half way thru the trunnion then welded over. I am guessing that is why the barrel was welded to the trunnion.3682136822

bladeworks123
02-02-2013, 07:48 PM
Wow,,,,That's a new one... How sure are you that that was a Century built rifle and not a home build on a Century Receiver?

hywayflyr
02-02-2013, 09:24 PM
I have no history on the rifle at all. It was bought by a friend and he ask me to check it over. The lack of bolt gap was not the only problem. The trigger group and housing did not fit properly resulting in a failure to eject and the magazine well needed to be reworked to lock a magazine in.

rustypirate
02-03-2013, 02:27 AM
That sounds like a home built gun on a Century reciever.
Century did not remove barrels from the trunions in nearly any of the CETME rifles that they built, so the fact that the barrel pin was not installed correctly would indicate a home build to me.

bladeworks123
02-03-2013, 11:32 AM
It's a shame that the trunnion and barrel have been trashed. With some very careful work, someone could save that receiver. You would end up replacing the cocking tube, barrel and trunninon. But it would be worth it. I have a home build gun on a cast receiver that went bad. Someday when I have the time I am going to demill it just for the receiver. The cast receivers make a really nice rifle if done right.

bladeworks123
02-03-2013, 11:45 AM
With all the welding that was done on that trunnion, you want to check it to make sure that it has not been annealed to the point that the roller locking shoulders are soft now. That is what happened to the rifle I picked up. It lost all of it's gap in the first few rounds that it was fired. The fellow who built it, not knowing better, welded on it getting it really hot, and then quenched it in water to cool it off after each weld he did. You can check it by using a small triangular needle file on the leading surface of the locking shoulders. If you can easily file a mark in the shoulder area of the trunnion, you will need to replace the trunnion. On a good trunnion, it is very difficult to get a file to even scratch the surface.

hywayflyr
03-08-2013, 07:31 PM
Ok, finally got a chance to update this thread. I had a friend in the materials lab check the trunnion for hardness, all was good. I was able to rework the barrel pin hole in the trunnion and the barrel was pressed in and pinned with a oversize pin. Bolt gap was set at 0.0195". We took the rifle to the range and ran 200 rounds through it with no failures. Bolt gap settled at 0.014". Owner was able to shoot 5 round 6" group at 100 yds. Everyone is happy with the out come. I appreciate all the info and advice provided by the members.