There are many occasions that I can't get my MIG gun into a place very well. Because the head on the gun is so big.
I imagine if I were building a header, some of the tight spots in between runners might give me trouble.
Sometimes I'm so deseperate I unscrew the defuser, but it doesn't shield very well then. :P
Any tips? I know I should be using a TIG. but.. gotta use what you've got at the moment.