"Just followed card settings on the front of 252."
Man, this is really strange - you got me curious so I went looking - the cards on the front of MY 252 (about a 5 yr old machine) don't show ANY voltage settings above 25.5, so I got even MORE confused - checked the miller online calculator
Miller - MIG Welding Calculator
And it doesn't even HAVE settings for 1/2", except for spray transfer with .045 wire.
Then I checked the mm252 .pdf I downloaded last year, and found your settings - 1/2" steel, .035 wire, 29.5 volts @515 IPM with C25 gas.
Your machine is newer than mine, so somehow those numbers must have been changed
AFTER mine was built. I'll see if I can find the paper manual that came with mine and compare those #'s, but I can sure see why your welds were kinda hot
The 3/8" settings in the newer manual are quite a bit higher voltage as well, compared to the online calculator and my older machine's cards, but 1/4" settings are nearly identical for old and new.
Personally, I think you might do better ordering one of the "slide rule" mig calculators, they're about $5 - I keep one with my machine 'cause the front cover is a PITA to open and close, and because I don't wanna go online every time I change settings.
At the voltage settings they call for now, I don't see how you'd keep from going into globular transfer... Steve