I also found that often the welding wire would stop arcing and the wire would keep pushing against the metal. I would often have to let go of the trigger and pull the trigger again to get the arc going. Anybody any idea what could be causing that?
I had the gas set to 10 litres a minute. Is this enough?
The first thing sounds like either a wire feed issue or on oversize or knackered contact tip.
To feed properly the wire needs to be absolutely free from rust. Also, the tension on the wire feed should be such that by holding the wire between finger and thumb, with the trigger pressed, you can slow down (and eventually stop) the wire coming through by increasing finger and thumb pressure.
10 litres per minute is almost certainly too much. Try 5.
I am practicing using 6mm mild steel.
I couldn't have been getting full power as I think my penetration was maybe only 40% max after multiple tries on the highest power setting. Anyone know what might be going on with that??
You won't do 1 pass welds on 6mm steel with a 180amp MIG. You need to root the joint and do 2 passes, maybe 3.