I have been doing a little research on this by visiting with a friend who has trained in it and has done quite a bit of TIG welding. He tells me that the TIG welder should be used in D.C. Reverse mode, and that there are several different gases that can be used with it. He seemed to think that if I was getting pin holes in the welds that it was either caused by impurities in the metal, or that the man doing the welding was using the wrong gas for the type of welding he did for me.
Apparently, there are different gases to be used with stainless, chrome moly steel, aluminum, and cast metals. He also told me that sometimes they will use the gas that is not so good for the purpose because it saves them money. I would appreciate any input from members who have had some experience in this field so that we can figure out how to end the problem of pin holes in TIG welds on our double guns. One more thing I want to mention is that there has been talk by a few people on here about the possibility of tig welding barrels into the monoblocks. This is a mistake in my oppinion, and should never be done. As Bramble stated in another post, welding on the monoblock could cause embrittlement of the steel, and there is no way to then anneal it back. Barrel joints need to soldered with good solder after having been carefully fitted. I don't know if just welding over lettering would cause harm or not, but after thinking it over, I have decided, for myself, that I won't do it. There is too much chance for error. It might also heat shrink or distrort a perfectly reamed monoblock to go welding on it after it was formed.