I've used a micro torch successfully on Argentium, though I wouldn't
want to do it for lots of jump rings...but if you don't have any
other torch, then that should do. What gauge metal are you using? I
used mine on 22g. The 20g was just too time-consuming, so I went to
my acetylene torch. I'm going to guess anything thicker than 20g
isn't practical with a small torch.
Are you using a charcoal block? If so, that could account for where
all your heat is going, and the ugly results on the metal.
If you are not on charcoal, and if you really do have Argentium,
then I'm stumped. With a small torch like you have, I'm not sure what
other test you can give the metal.