i am a master of this as i had to do several smokers. the best way is with roloc pads. its sand paper but only 2" or 3" round. the best to use is a 90 degree air grinder (talk to a mechanic friend). all these items are small and can get into little spaces. it will get all but the rust in the pits. for that i have used navel jelly and some other product (can not remember the name) that seemed to work a little faster but it was a lot more expensive. the later of the items i purchased at home depot in the paint section next to the acetone, it was on the bottom row. just look for the most expensive rust remover, the lesser ones work ok but this one was a lot faster and more thuro (i have no idea how to spell that word, hopefully you will know what i am saying), i only had to do it once not 2 or 3 times.
if you dont have the means to that the next best thing i found was aluminium foil. you will go through it some what quick so dont make big balls of it, once the foil smooths out and fills with the rust you will need a new piece. i do like this method the best as it is not using chemicals and it probably something you already have around the house.
you will want a respirator or mask as it gets really dusty and you will taste the rust in your mouth and lungs for a few days after words.
however i think i really like the idea of the M80. im going to try that next time, then finish up any loose ends with the foil.
i am also thinking of genetically altering the DNA in termites to eat the rust
