I have a Miller Mig. Love it! I use .023 on sheet metal. I use CO2 for my gas mainly cause I own two restaurants with my brother and we have the CO2 tanks readly avaliable for the coke machine. Plus the tanks are shorter. It shelds the arch just fine. Spot welds is the way to go I let the wire come out bout a inch and half on the gun. The longer distance seems to do better to prevent it from burning a hole in my work. Even on the lowest power setting. I turn the gas pressure up a little more also. Practice and trial and error is what it took for me to get it right.