[Tim Brewer]

You can use shielded wire in any mig machine, but you must reverse the polarity first. The polarity works opposite than when using gas. But in my experience, the welds are always better when using gas. But when welding outside, shielded gassless wire seems to work best because if there is any wind at all, it will dissapate your argon and give you a bad weld. Not an expert or anything, but hope this help a bit.
Tim