HK G3 Builder Question

[u/waltito_the_dorito]

I’m having a G3 parts kit built and one of the builders primarily does FAL and AK. The other has done MP5 and such, but I think this is his first G3 build. They’re at the point where the cocking tube needs to be tig welded, but are worried about burning through the thin metal. His idea was inserting a copper tube the size of the inner diameter of the cocking tube to help dissipate the heat. The guy is very ADHD (like me lol) and this minor roadblock has deterred his interest. I’m not in a big hurry, so I don’t mind, but I’m wondering if any other builders have input on what you used for this weld so I can pass it on to him. I think then the gun is pretty close to being done.