No corrode contains corrosive salts
Great to know,,,but I don't use (Trade Name) No-Corrode Flux,,I use a Paste Flux stuff in a plastic jar from Home Depot. It doesn't corrode anything. Oakley or Oatley is the name on it.
Works on copper plumbing, wiring as well as Purdey, Parker, Fox, etc SxS ribs.
....But (older) people commonly call any paste flux stuff No-Corrode Flux.
I failed to mention in using c-clamps that positioning a couple to hold the bbls side to side from separating can be done as well.
It's not really needed if you are careful, but I usually do use one at the muzzle.
Actually if you are using clamps and you are able to compress the ribs enough to push the bbls apart while sweat soldering the ribs into position, then you are using way too much clamp pressure and allowing too much of the rib & bbl to get to soldering temp at one time. No need for either.
Yes you have to be careful with what you use and how you use it.. and what works for one person may be a complete bust for another. Results are what count.