Since I wrote this post, I have been soldering the 40mm quad mounts (Eduard) with decent success. I don't have a resistance unit, although I'd really like one. I'm using a Weller temperature controlled soldering station with the setting at three. I'm also using TIX solder with is a non-lead, very low melting point alloy with decent tensile strength. It has its own liquid flux and both are available at MicroMark.
I tried using CA and was very disappointed with the results especially when trying to get the plastic guns to stay put between the gun stands. I ended up actually drilling both and mounting the guns with 0.020" brass wire. It's finicky work, but the results are decent and the guns actually move.
I am very lucky. I received a complete 2nd set of Eduard PE when I asked them to replace some parts that broke during assembly. I've been making good use of the second set. In fact, I've been building the guns out of this set since the first set was primed and painted haze gray and that makes soldering even more challenging.
It's also very good that I have another set since the scrap rate is very high due mostly to parts de-soldering when soldering added parts. I try to manage the the heat closely, but unless the heat transfer is very fast, the whole part gets hot and parts start disconnecting. Once that happens it's almost impossible to get it back together correctly.
I'm doing a complete build thread on WorldAffairsBoard.com at
http://www.worldaffairsboard.com/modele ... iling.html. It has many pictures following the whole soldering process. It also shows and talks about some of the screwups that occurred also.