ugh...don't do it.
if you want something rugged, get a can of engine enamel.
engine enamel is a good option. many contain ceramic, which makes it a harder finish, and it self-levels better than paint. you still need to disassemble/strip/prep for best results, and take your time finishing it. the biggest obstacles to a good spray paint job isn't the spray paint— it's your prep and painting technique.