Welding upside down with a mig usually requires a little cooler heat setting. That is when using a properly sized welder.
You'd probably do better with a bigger welder, that 110 won't do anything thicker than 1/8 without preheating. You could also try straight co2.
I have one of those 110 lincolns on gas and I won't use it on anything over 1/8 ...period.
my signature lines...not really directed at anyone in particular..
BE different....ACT normal.
No one is completely useless..They can always be used as a bad example