MAPP with O2 SHOULD be fine. You only need enough heat to melt the material, and MAPP is sufficient for this task, as is propane and natural gas when used correctly. From memory, in order of potential BTUs, Natural Gas, Propane, MAPP, Acetelyene. I may be wrong, but the point is, Acetelyene is the hottest, with MAPP the next hottest, and propane below that. All of them will work. MAPP by itself will probably work too.
See my edit. Brazing and Soldering creates a bond with the metal, so unlike a screw, it will NOT twist out cold, but will have to be heated and reversed, or drilled and retapped in order to remove it. If you try to extract it as if it were a bolt, at best you'll wollow out the hole you made for the extractor, at worst, you'll break the extractor.
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