flux core wire gives a nasty appearance as compared to solid MIG wires. The shield flux is in the center of the wire and burns as you weld to make the shield gas cloud over the arc..makes for a mess its even messier than stick! Ive seen an automated setup running MIG flux core wire,.045dia,350amps and it used shield gas as well over the flux core wire,multipass welding heavy 2"structural plate sections.Why they ran shield gas with flux core I don't know. They were ending the run, the guy I knew gave me a couple 4or5 35lb rolls of the wire and I tried it on my MIG machine and it didnt run for squat here,had to make adjustments and change out my liner to run it too.I think it's still out back in the storage container..why do I keep that stuff? I tried many different settings and feed speeds,just couldnt make it work..so ER70-S6 solid core it is for me for 90% of what I do.. I'd go back to using stick over flux core,at least I know where I'm at with running a stick electrode