I have a variety of 3 G3's that have broken or damaged cocking tubes.
Can anyone tell me the best way to gain access to replace this piece?
One of them is built on a aluminum FAC upper the other 2 are sheet metal, I have not been able to determine weather it would be easier to press the barrel out, or attemp to remove the sight bracket at the front of the barrel? Hell so far I am not even sure what holds the sight bracket and muzzle break on!! I think that items is welded but am not sure, perhaps someone can shed some light on that for me as well.
And last, assuming that it is going to be easier to un-press the barrel to replace the cocking tube, is there anything other than the one pin (rivet?) holding it in the trunion? Also on the Aluminum model does that pin hold the trunion in as well??? Obviously on the sheet metal models the trunion is welded in, but not sure about the Aluminum model.
Well thanks for any help ya'll can provide, haven't been around in awhile but perhaps I can catch up with old friends from here at the next BRC! :>
Ok Thanks again for any help ya'll can provide will check the board frequently for awhile to look for any feedback on this problem I am having. Thanks RemMax

On the Aluminum receiver model, the screw at the front sight is all the holds the cocking tube in place.  By removing the screw/pin, you can change out the cocking tube with the barrel still attached.

As for the steel receiver, to change the tube, you would need to grind down the weld, install a new tube and weld.  The problem with having to remove the barrel is that when you press the barrel back in, you will need to re-index the sight.  The barrels will never press back into the trunnion the same way (barrel index) twice.